Media playback is unsupported on your device Media caption As Damian Grammaticas reports, the activists were detained after taking photographs with banners urging officials to disclose their assets

China has put three anti-corruption campaigners on trial, in what is being seen as part of a crackdown on activists under President Xi Jinping.

The trial of Liu Ping, Wei Zhongping and Li Sihua, activists associated with the New Citizens' Movement, began in Xinyu, Jiangxi province, on Monday.

They were detained after taking photographs with banners urging officials to disclose their assets.

Mr Xi has called for a crackdown on corruption since taking office.

Ms Liu, Mr Wei and Mr Li were arrested in April.

Analysis Xinyu, where this trial is taking place, is a gritty, polluted place - rows of grey concrete apartment blocks and giant factory chimneys. It is perhaps an apt setting. A year ago, when Xi Jinping took over as the head of the Communist Party, some hoped a new, younger leader might bring reforms to China, more tolerance of critics, more freedoms. Instead, with this prosecution in this gritty city, those hopes for change have faded. Mr Xi appears to be overseeing an intensifying crackdown that goes beyond anything his predecessors did, designed to reinforce his authority and that of the party too. It is no longer only human rights activists who are being targeted by the authorities. Lawyers, bloggers, businessmen and, as in this trial, even very low profile, local campaigners are being detained, some for doing little more than staging peaceful, public protests against corruption, calling for the rule of law, for more civil and political rights for ordinary people. What worries observers is that under Mr Xi, China may be getting less tolerant, basic freedoms for people to gather and express their views are being violated, so too is the right to a fair trial. In this case, defence lawyers say police detained key defence witnesses ahead of the trial.

They were initially detained for subversion, but the charge was later changed to illegal assembly, activists and lawyers say.

Zhang Xuezhong, one of Ms Liu's lawyers, told Reuters news agency that "serious procedural problems" had been found in the case, and he was "not optimistic" about the trial.

Defence lawyer Pang Kun also told reporters that he had been detained by police on Sunday.

Tight security was in place for the trial, with lines of police blocking roads outside the court.

A number of Western diplomats who had attempted to attend the trial were blocked from entering the courthouse, AP news agency reported.

Liao Minyue, daughter of activist Liu Ping, told AP they were "still a little bit confident in this case".

UN criticism

Since Xi Jinping took over the leadership of the Communist Party a year ago, his government has launched its own anti-corruption drive, the BBC's Damian Grammaticas reports from outside the court in Xinyu.

But Mr Xi has also overseen the broadest crackdown China has seen in recent years, our correspondent adds.

Several activists in the New Citizens' Movement, which calls for more democracy and government transparency, have been detained.

In July, prominent lawyer Xu Zhiyong, one of the founders of the movement, was detained on suspicion of having "gathered crowds to disrupt public order".

New Citizens' Movement A loose network of activists in China

Campaigns for more civil and political rights in China, and educational rights for children

Has urged officials to declare their assets to help combat corruption

Members have organised mealtime gatherings to discuss social and legal issues

Earlier in October, wealthy Chinese businessman Wang Gongquan, who is considered a key supporter of the movement, was also formally arrested on similar charges.

"Liu, Wei, and Li are canaries in the coal mine for how the government intends to treat this influential group of anti-corruption activists," Sophie Richardson, China director of Human Rights Watch, said in a statement.

"Anything short of acquittal will seriously undermine the credibility of the government's claims to be cracking down on corruption," she added.