Hundreds of disgruntled property owners protested at a Shanghai apartment complex yesterday as construction workers began to remove the remains of a building that collapsed more than a month ago. About two dozen owners wearing matching T-shirts climbed on to the roof of an adjacent building in the unfinished estate at about 2pm after hearing the fallen block was being removed. 'Rebuild Lotus Riverside,' they shouted. 'Knock down all the towers.' Police cordoned off the site and surrounding roads, but more angry owners arrived throughout the afternoon, crowding outside the estate's main gate and at times coming to blows with security guards. 'I came out to protest after I saw on the internet that some other owners were already here,' one said. Occasional showers failed to calm the highly agitated group of about 200 who remained camped outside the development until late at night. They repeatedly chanted the name of Shanghai Communist Party secretary Yu Zhengsheng in an attempt to gain the attention of high-level officials. A 25-year-old teacher, who gave only his surname, Zhou, said: 'We hear the people on the roof are planning to stay all night. If they don't leave, then we won't, either. Otherwise it would be like betraying them.' The owners of flats in the estate's remaining 10 towers are in a deadlock with the property developers over a compensation settlement. They have until August 15 to decide whether to accept a 5 per cent rebate on the cost of the property, take a full refund of all monies and interest paid so far, or sell their property to the new developer after a government-appointed inspector sets the value. The project was taken over by Shanghai Vanke Real Estate on Saturday after the operations of the original developer, Shanghai Meidu, were suspended over the accident. However, many owners say they remain unhappy with the settlement on offer and are demanding an independent investigation amid accusations of local-government collusion with the developer. 'We have the right not to accept any of their three options,' said one owner, who gave his surname as Xu. 'They are trying to take away the evidence, because so far there still has not been an independent investigation into this building.' Mr Xu said owners had received assurances from Minhang district authorities at a meeting on Saturday that the fallen building would not be touched ahead of the next round of negotiations, set for this Saturday. The 13-storey building, in the 11-tower Lotus Riverside complex, toppled on June 27, killing one worker. Its foundations had been undermined by excavation work for an underground car park being built alongside. Waste earth removed from the pit had been piled on the other side of the building, and the weight contributed to the collapse.