Two Chinese anti-corruption activists went on trial on Thursday, their lawyers said, as a key funder of their rights movement was bailed after apparently confessing to authorities.

The proceedings against Zhao Changqing -- a student leader during the 1989 pro-democracy protests in Tiananmen Square -- and Hou Xin are seen as part of a crackdown on the loose-knit New Citizens Movement.

Its members face up to five years in prison for their roles in small-scale protests calling for government officials to disclose their financial assets, seen as a key reform against graft.

The ruling Communist Party says it is conducting its own anti-corruption campaign, but Beijing is extremely wary of any organised dissent against its rule.

China's government has also objected to a global media investigation that said relatives of top leaders -- including kin of President Xi Jinping and of former premier Wen Jiabao -- used offshore tax havens to hide their wealth.

Zhao's trial -- which followed that of New Citizens Movement founder Xu Zhiyong on Wednesday -- opened in Beijing but was halted almost immediately as he sacked his lawyers, one of them, Zhang Xuezhong, told AFP.

"This dismissal was a tactical choice by the defendant because this was the only way to halt the trial," he said, adding the move gave Zhao 15 days to find a new legal representative.

Hou's trial took place on Thursday afternoon, her lawyer Ding Xikui told AFP, adding she pleaded not guilty and it was unclear when a verdict would be announced. Hou has been released on bail for health reasons.

The activists are all but certain to be convicted by China's politically controlled courts.

Zhao, who like Hou is in his mid-40s, has served two prison terms totalling eight years since 1997 for his continued activism.

His trial came as Wang Gongquan, a multi-millionaire backer of the movement who had been held since September, was bailed after he apparently distanced himself from other activists.

Wang, a venture capitalist who is said to have provided funding for Xu, was released after confessing that he had helped "organise and incite criminal activities", according to a statement by a Beijing court late Wednesday.

The release indicates that Wang will not face trial.

Xu's lawyer Zhang Qingfang said the announcement was intended to "mislead public opinion" in his client's case.

"Wang cannot admit a crime as the court said, because there is absolutely no evidence he ever committed a crime," he told AFP.

Founder speaks out

The New Citizens Movement is tiny but has developed in recent years with organised dinners to discuss various causes -- from education equality to official graft -- and has held small, sporadic street protests.

Between 20 and 40 other activists linked to the movement have been detained since 2013, members say. Three were put on trial in the central province of Jiangxi after they posted photos of themselves online holding signs urging official asset disclosure.

The arrests have been seen as part of a broader campaign to enforce ideological unity since President Xi took charge of the Communist Party in late 2012.

Xu Zhiyong's prosecution was condemned by international rights groups, as well as the US and the EU -- criticism dismissed by China's government as interference in its internal affairs.

US ambassador to China Gary Locke Thursday said he was "deeply concerned" about the trial of Xu and other "good-governance advocates" and called for their release.

"The United States Government calls on Chinese authorities to release Xu and other political prisoners immediately, to cease any restrictions on their freedom of movement, and to guarantee them the protections and freedoms to which they are entitled under China's international human rights commitments," he said in a statement.

Xu remained silent through almost all of his hours-long trial on Wednesday in protest at the court's handling of the case, his lawyer said, but later spoke for around 10 minutes before he was interrupted by a judge.

"The New Citizens Movement supports freedom. Justice and love are the movement's spirit," Xu said, according to an account of his speech circulated by his supporters and verified by Zhang.

Xu's trial coincided with the release of the report by the International Consortium of Investigative Journalists, which said that Xi's brother-in-law and Wen's son and son-in-law were among those with offshore holdings.

Chinese foreign ministry spokesman Qin Gang said "ulterior motives" may have underpinned the investigation.