China's top-ranked diplomat intensified pressure on Japan on Sunday, warning Tokyo against making "misjudgements" over the seizure of a fishing boat.

Chinese officials straining to stifle protest ahead of a key Communist Party congress have been paying to have troublesome petitioners held in violent squalor in a secretive Beijing prison, many complainants said. Eight petitioners told Reuters of being held in the prison with dozens of others who had come to the capital to press grievances.

A prominent human rights lawyers in China remains missing three days after he called his wife to say he was led away by state security police.

China said on Tuesday that a US Navy ship involved in a confrontation with its fleet off Hainan had violated international and Chinese laws.

Chinese forces have fired tear gas to break up a protest by Tibetans in the province of Sichuan, the latest flare-up of volatile unrest there.

China's millions of rural workers will become a serious threat to stability unless they are better treated in their new urban homes.

Japanese firms have shut factories in China and urged expatriate workers to stay indoors in the wake of angry protests over a territorial dispute.

Chinese leader-in-waiting Xi Jinping's visit to the US next week could set the mood for the next decade that he is likely to serve as president.