US resident accused of fraud but supporters say charges are punishment for years of activism

A long-term US resident and former leader of student protests in Tiananmen Square went on trial in China this morning, one day after Barack Obama concluded his visit to the country.

Zhou Yongjun is accused of fraud charges involving a bank in Hong Kong, his lawyer and his girlfriend told Reuters. She and other supporters said they believed the charges were a pretext to punish him for years of activism. Zhou was a leader of the Beijing Students Autonomous Union and was jailed for two years following the bloody suppression of the 1989 protests.

"I know from the lawyers that he's on trial today, but the whole process has been kept secret," Zhang Yuewei, Zhou's girlfriend, said from Los Angeles where she lives. She said Zhou's immediate family had told her of the trial in Shehong county, in the south-western Sichuan province.

In an email to Reuters, she added: "Holding the trial at this time was to show the US president ... the Chinese government maybe believes that it has the power and cash to go up against the United States and international society."

Obama raised human rights concerns with senior leaders during his trip, and spoke publicly about why America believed rights such as political participation were universal, but some campaigners had hoped he would go further.

Zhou, 42, was handed over to mainland authorities by Hong Kong officials in September last year. It is thought he had hoped to visit relatives using a Malaysian passport.

Although Hong Kong was returned to China in 1997, it has separate political, legal, economic and immigration systems from the mainland. Hong Kong's government refused to comment on Zhou's case. Visitors whose travel documents do not meet requirements were usually returned to their "place of embarkation or origin", the government said.

Zhou has a US green card giving him residential rights in the US but not full citizenship – meaning the US has little formal power to intervene.

Zhou's lawyer, Chen Zerui, told Reuters: "Of course, he pleaded innocent and spoke out to the court in his own defence.

"He believes the whole case is without any foundation."

Chen told the Associated Press that the passport Zhou was using was in a name on a money laundering watchlist, but that the defendant said he had obtained the passport through an immigration agency and had simply been the victim of bad luck.

According to the Hong Kong-based Information Centre for Human Rights and Democracy, the name is a pseudonym used by the deceased leader of a meditation group banned by China and authorities suspected Zhou of attempting to access funds frozen after the leader's death. Bank officials say they spotted a suspicious request for a transfer of funds.