Shanghai warned protesters they would be punished if they tried to travel to Beijing to petition the government around the time of the Olympic Games, said lawyer Zheng Enchong , the city's best-known political dissident. Mr Zheng, who has advised hundreds of Shanghai residents in cases against the government over eviction and compensation for relocation, added that surveillance of his own activities had recently increased. He confirmed claims by a human rights group that local police had advised dissidents against leaving Shanghai and speaking to foreign journalists, though he said they were verbal warnings and not delivered in a specific document. 'The officials want to protect themselves,' he said. Some officials had also told petitioners seeking to travel to Beijing that they would be warned and returned to Shanghai on the first attempt, detained for at least 10 days on the second try and face 're-education through labour' on the third, he claimed. Protesters often seek to take their grievances directly to the central government in Beijing because of indifference or interference by local-level officials. Shanghai authorities usually try to stop petitioners while they are en route to Beijing or return them to their home cities after they arrive in the capital. Mr Zheng was released from jail in June 2006 after serving three years for 'leaking state secrets' and contacting an overseas human rights group.