* 20 anti-corruption activists detained
* Six more activists to be tried on Thursday and Friday
* Three activists awaiting sentences
By Sui-Lee Wee
BEIJING, Jan 22 (Reuters) - When dozens of activists unfurled banners across the country last March and April calling for officials to disclose their assets, they did so at the urging of one of China's most prominent rights advocates, Xu Zhiyong.
Through his online essays and Twitter account, Xu criticised the government's efforts at fighting corruption and prescribed democracy and the rule of law as the solution. "When more than 90 percent of the officials are corrupt, who will counter who? The social movement of asset disclosure is an effort for gradual change to the system."
Xu, 40, stands trial on Wednesday on a charge of "gathering a crowd to disturb public order" punishable by up to five years in prison. His case will almost certainly spark fresh criticism from Western governments over Beijing's crackdown on dissent.
The government has waged a 10-month drive against Xu's "New Citizens' Movement", which advocates working within the system to press for change. The campaign against the movement exposes shortcomings in Beijing's bid to root out corruption, even as the authorities claim greater transparency.
China has detained at least 20 activists involved in pressing for asset disclosure, though not all are from the New Citizens' Movement. Six will stand trial in Beijing and the southern city of Guangzhou on Thursday and Friday.
Three stood trial in December and face more than 10 years in prison if convicted.
"The Communist Party does not accept pressure, the party does not accept challenges," said Chen Min, a writer and friend of Xu's. "Anything that the party can't control, independent and non-governmental forces - no matter how gentle the force - it has to combat."
Friends of Xu, whose wife gave birth last week, say he remains unafraid. In a video-taped message from a detention centre issued last August, Xu, wearing handcuffs and an orange vest, urged the Chinese people to fight for their rights.
Xu's case will be China's highest-profile dissident trial since 2009, when Nobel Peace Prize Laureate Liu Xiaobo went on trial for subversion after he helped organise the "Charter 08" petition urging the overthrow of one-party rule. Liu was jailed for 11 years.
Xu's trial is expected to draw many supporters. Hu Jia, a prominent dissident, said state security officers told him and five other activists not to leave their homes.
Rights groups have criticised the crackdown on anti-corruption activists and called for Xu's release.
"I think this crackdown on him and other activists who have been associated with the New Citizens Movement is really a very hypocritical step of the government itself that says its goal is to crackdown on corruption," Roseann Rife, head of Amnesty International's East Asia department, told Reuters in Hong Kong.
U.S.-based Human Rights Watch, in a statement linked to its annual report issued on the eve of the trial, said China had "yet to embark on fundamental reforms that adequately respond to the public's increased demands for justice and accountability".
Xu taught law at a Beijing university and ran in a local election. He became prominent over a drive to abolish "custody and repatriation" powers, a form of arbitrary detention used by local governments to sweep homeless and other undesirables from the streets. The government scrapped the system in 2003.
Xu has also campaigned for the rights of children from rural areas, who lack the required residence permit, to be educated in cities where many live with their migrant worker parents.
The Chinese leadership is nervous about Xu's writings, which "have become part of the mainstream opinion", Chen said.
Xu has more than 50,000 followers on Twitter, which is blocked in China but can be accessed by virtual private networks that can bypass China's Internet blocking mechanism. His name is blocked on Weibo, China's version of Twitter.
In 2009, Xu was briefly arrested on tax evasion charges his defenders said had been trumped up in a bid to stifle his work. The charges were dropped after a public furore.
"He is a person with very pure ideals, he is very resolute about his ideals and will disregard his own personal interests for them," said Xiao Guozhen, a lawyer and a longtime friend of Xu's. "He is carrying a cross for the Chinese people." (Additional reporting by Venus Wu in Hong Kong; Editing by Ron Popeski)