Wary of the danger of flaring nationalism backfiring on the government, however, authorities were on high alert. They strengthened security to minimise the scale of protests and stepped up surveillance of dissidents and rights activists across the mainland.

In Beijing, dozens of protesters, mostly in their twenties and thirties and including university students, gathered in front of the Japanese embassy under a chilly shower at 9am.

They chanted 'Free the captain', 'Down with little Japan', ' Give us back the Diaoyu islands' and 'Don't forget national humiliation. Don't forget September 18'.

The uninhabited Diaoyu Islands, which contain rich fishing grounds and possible oil deposits, are claimed by Beijing, Taipei and Tokyo, which calls the islands the Senkakus.

The area surrounding the embassy compound was condoned off yesterday morning by hundreds of police, plain-clothes officers and armed soldiers, and protesters were not allowed to get close. Many said their placards were taken away by policemen before they were allowed to join the protest.

Although police tried several times to disperse the gathering crowd, protesters managed to march through the area, home to numerous diplomatic missions, the US ambassador's residence and the headquarters of foreign ministry.

At least three protesters were taken away by police in front of photographers and cameramen from the domestic and international media. Among them was Zhou Xu, who said he rushed to Beijing overnight from Anhui province for the demonstration.

Wearing a T-shirt with a slogan which read 'Japan, get out of the Diaoyu Islands', Zhou said he planned to stage a sit-in in front of the embassy to demonstrate 'Chinese people's determination to defend China's territorial integrity'.

But he was soon taken away when he claimed he had been persecuted by authorities for being a patriot and vented his anger at the government's diplomatic weakness in dealing with Japan.

Many petitioners attended the protest, calling themselves patriots. Protesters also chanted the Chinese national anthem along the demonstration route and occasionally yelled slogans such as 'Boycott Japanese goods', 'Americans get out of Asia,' and 'Wipe out the Japanese devils'.

But bad weather deterred more from turning out, according to protesters and many onlookers. Analysts believe the 'stability maintenance meetings' held by many Beijing universities on Friday to warn students against joining the protest also successfully deterred students from participating.

The mostly peaceful protest came to an abrupt end near noon when demonstrators who wanted to march to the Japanese embassy were surrounded by at least 200 policemen and were ushered away.

In Shenzhen, hundreds of protesters carrying Chinese flags took to the streets in the city's busiest business district, shouting 'Return the Diaoyu Islands to China' and 'Patriots are innocent'. The rally began at around 10.30am at Huaqiangbei and lasted about 30 minutes before police, who outnumbered protesters at least 15 to one, dispersed the crowd.

An angry protester lambasted the mainland government as being too weak to protest against the Japanese and their wrongdoings. 'Look at the South Koreans and their government. We come here to support our country but the government wants to take us away,' he said.

Big electric appliance shops selling Japanese brands hired thousands of security guards because of fears that protesters would smash their stores as they did five years ago.

Xinhua said in an English dispatch that protesters gathered outside the Japanese consulate general in Shenyang and chanted anti-Japan slogans.

In Shanghai, at least two anti-Japanese protesters were arrested as hundreds of police swarmed the streets around the city's Japanese consulate.

At its height, barely 20 people were involved in the protest.

However, the demonstrators became more heated when police parked a large tour bus directly in front of them, blocking their line of sight to the consulate, and then moved to clear the road at 11am.

'Traitors. They're all traitors,' yelled one protester as the police drove the small crowd off the street and away from the consulate.

'Is it a crime to love your country now?' screamed others as they attempted to prevent a bus carrying the arrested demonstrators from leaving the scene.

Well over 200 police were deployed to the area and closed off the road passing the consulate entrance.

The Chinese characters for 'Japan' on the signage of a nearby Japanese drinks shop had been papered over, along with Japanese-language menus in the window, apparently out of fear of reprisals.

A spokesman for the Japanese embassy said he hoped that the demonstrations would not damage bilateral ties.

Highlighting Beijing's concern over unrest, rights lawyers such as Teng Biao and Xu Zhiyong and several dissidents were under house arrest or briefly detained yesterday.

Professor Pang Zhongying of Renmin University said the government's handling of the protests underlined Beijing's dilemma in dealing with nationalism.

'Beijing does not want give others the impression that it encourages nationalism as both China and Japan are trying to find a way out of the row, which is unlikely to last long,' he said. Beijing was clearly worried about nationalism, which could easily backfire on the government given the more pressing social and economic woes on the mainland.

'Nationalist sentiment may be useful in wooing public support to resolve diplomatic rows, but it can get out of control and fuel dissatisfaction towards the government,' he said.

Shi Jiangtao, Will Clem, Fiona Tam, Stephen Chen and Raymond Li