The forced demolition came a year after threats from local thugs, who had been hired to dump garbage and earth on the families' farmland. The village organisation, which had been trying to remove the families, had already cut off their water and electricity and obtained a court order demanding they move out of their homes but without compensation.

Cai and her neighbours' homes stand in the way of a plan by the Ningbo government to turn the area into a business, logistics and leisure centre. The families did not receive compensation because they are immigrant farmers and do not belong to the village economic co-operative, which owns land on behalf of farmers.

'I'm infuriated by the thought that helpless farmers are getting locked up for simply refusing to give up their rights,' said Wang Ling, a lawyer at the Beijing-based Cailiang Law Firm, who is representing 34 families seeking compensation. 'If you force them to move without compensation, where will they live?'

Immigrant farmers are among the latest victims of the mainland's aggressive urbanisation, which often results in forced removals despite Beijing's repeated notices to discourage such harsh measures. The farmers are the weakest of the weak. They were lured in the thousands by local governments from the country's interior nearly three decades ago to work the rich farmland along the coast. In Ningbo alone, 31,000 farmers agreed to move to nearby villages from poorer parts of Zhejiang from the early 1980s to the 1990s, according to government research.

Immigrant farmers have come into conflict with the Ningbo government over development in other districts. And clashes with local governments have erupted in other parts of the mainland - in Xibei Wang village in the suburbs of Beijing, in Foshan in Guangdong province and in the Haizhu district in Guangzhou, according to lawyers at the Cailiang Law Firm. Some who resisted are still locked up in kan shou suo or detention centres, while many have been left homeless and destitute. Only a small group of lawyers are still fighting local governments for compensation for immigrant farmers.

These farmers are especially hard to defend because, as immigrants, they do not have the same rights as local villagers and they have no signed contracts to verify their claims on their homes.

Zhu Xiaoding, another lawyer at Cailiang, is defending two immigrant farmers being held in custody. Zhu said the basic issue was local governments' defiance of established regulations and laws.

The Ningbo government set out instructions for relocating immigrant farmers in 2004. The notice, titled No 141, states district governments should provide economic compensation to immigrant farmers whose 'temporary production and living accommodation is demolished'.

'But when it comes to reality, so many local officials defy the rules and there are no consequences for such violations,' Zhu said.

One reason why local governments ignored the rules was the lucrative share of the proceeds they received from land transfers, Zhu said. Local governments generated more than a quarter of their income last year from land transfers, according to the Ministry of Finance. That source of funds became even more important after the central government launched its 4 trillion yuan (then HK$4.54 trillion) stimulus plan following the global financial crisis in 2008. Local governments and state-owned companies were required to fund about 70 per cent of the package, according to various reports.

'I never thought that just by planting vegetables my father would end up getting detained,' said the child of a 55-year-old immigrant farmer who is still in detention, where he has suffered beatings according to other farmers who were present.

Lin Houxiang, 50, a farmer in the neighbouring village of Zhen Ai, was caught up in the conflict. He suffered a fractured right rib, according to a doctor's report dated May 9, one day after he was released from 11 days in custody.

The attacks on the villagers appear to have been well orchestrated by the local government. A township-level notice issued in Ningbo in February, literally translated, was titled 'The hundred-day attack and fortification', using wartime terminology for taking and holding ground.

It said that from mid-February to mid-June, officials would use about 100 days to focus on 'dealing with a series of remaining issues ... on land recall and demolition'. It divided the region and assigned demolition tasks to different teams. It said that by July 1 the teams would be evaluated on their performance and that the demolition efforts should 'mobilise all resources and everyone to attack and fortify'.

Today five immigrant farmers remain in detention for not obeying court orders to move out, which means they may face further incarceration.

At least nine farmers said they were physically attacked during the forced demolition, and three said they were beaten during detention in the Jiangbei district court.

For the first three weeks after Cai's home was demolished, she and her five family members slept on a blanket spread beside the pile of rubble that used to be their house. Afterwards, Pan Linmei, a neighbour, took the family in. But Pan's house and 25 others are also scheduled to be demolished.

Their rented farmland cannot be used because of the rubble piled up there, the farmers said. Cai and her family are now penniless and exist on whatever other villagers give them. Even her clothes were dug out from the rubble and trash.

The issues surrounding the demolitions are complex and the two sides agree on little. But essentially the dispute revolves around whether laws were violated during the forced demolitions, whether the immigrant farmers should receive compensation for the loss of their homes and help in relocating, and whether contract law should apply to the matter.

Bao Jun, the village head of Yaojiang, argues that no promises were made to the immigrant farmers to allow them to join the village economic co-operatives when they moved to Ningbo 30 years ago. Membership in the village co-operative is necessary to claim basic rights.

Bao and the village co-operative maintain that 'the forced evictions were based on court rulings' and that the farmers failed to pay their rent and, therefore, should be evicted.

Since the immigrant farmers have no written tenancy agreements, the village co-operative can stop renting the houses at will. Bao said the village notified the farmers to move almost a year ahead of the demolition, once in May and again in July of last year. The fact that the farmers stayed is a violation of village rights.

But Wang, the lawyer, counters that the forced demolitions were a 'violation of trust' on the part of the Ningbo government, since it invited the farmers to migrate in the first place to increase food production.

Wang said the forced demolitions violated notice No 141. He says the farmers have paid their share of the fees required of economic co-operative members. Therefore they should enjoy the rights of membership, which includes receiving relocation compensation, pension and health care benefits.

As for the contract laws that the local government cites, they were not established until 1999 and these farmers mostly moved to Ningbo around 1983.

'The law should not be applied retroactively,' Wang said. The farmers refused to pay rent only because they heard their homes were going to be knocked down and they never received the crop compensation the village promised. Wang says local governments rarely refuse to provide any compensation for relocations. Since he began representing immigrant farmers in 2004, he has seen district governments grant compensation to varying degrees, even to the full amount.

Hardly ever have farmers been treated with 'such outrageous force' as in Yaojiang, he said.

'Other districts in Ningbo such as Jiangdong, Haishu and Yinzhou have handled this issue much better,' Wang said.

The village economic co-operative said that in the government's notice No 141, the definition of 'temporary production and living accommodation' refers only to houses that were built by the farmers themselves. It does not include ones that were rented to the farmers by the government, according to court documents.

The Jiangbei district court and Ningbo City Intermediate People's Court sided with the village economic co-operative in its verdict on compensation.

'When these farmers moved over, it was the government that invited them,' Wang said. 'They have made a lot of contribution to Ningbo. You can't kick them away now that you don't need them any more.'

Wang said his firm was appealing against the compensation ruling and was representing two of the farmers in an effort to get them released.

The Ningbo Jiangbei District People's Court, which ordered the demolitions, declined to comment on the issue. 'According to notices issued by the Publicity Department of the Central Committee of the Communist Party of China, we do not accept interviews, respond or sensationalise on mass disturbances, and incidents that involve demolition,' said a court employee.

'Of course this is an incident involving mass disturbance.'

Government research and notices show that the Ningbo government does not deny the contribution the farmers made.

In a research report conducted in 2005 by Yu Weinian, the then deputy secretary of the Ningbo Municipal Committee wrote that among the immigrant farmers 'a substantial proportion was invited by the local government and villages to deal with grain production assignments', and that 'they made historic contributions to local agriculture'.

Yu wrote that 'some local officials still reject them [the immigrant farmers] and cater to the interests of existing co-operative members. This deepens the antagonism between both sides.

'Variances exist between practices and laws and regulations', and the city lacks consistency and coherence in the way it handled the issue of immigrant farmers' relocation issue.

Yu declined to comment further.

'In order to ease social conflicts ... and based on the fact that these farmers have made huge contributions, it is reasonable for the government to give compensation for the farmers' houses,' said Dang Guoying, an economist focusing on rural issues at the Chinese Academy of Social Sciences. 'It's not a lot of money, and it's not a complicated issue.'

Cai, the immigrant farmer, and 67 other farmers have marked their names with their fingerprints on a letter that shows their determination to stay on the land where they have lived for so long, until they receive compensation.

'We've treated Ningbo as our home, but they don't treat us as one of their own,' Cai said as she looked into the near distance where roads and new high-rises have replaced fields.

The worst is probably still to come. Zhu, the lawyer, thinks that ' the Jiangbei government wants to make an example out of this forced demolition', and that the real goal is to prompt the dozens of other families to move out quickly.

31,000

The number of farmers now living around Ningbo city who were lured by local officials to move in 30 years ago, to boost food production.