A former student leader of China's 1989 pro-democracy movement has been arrested on fraud charges, his family said yesterday, weeks before the 20th anniversary of the June 4 crackdown on Tiananmen Square protests.

The arrest of Zhou Yongjun, a leader of the Beijing Students' Autonomous Union in the 1989 protests, comes after months in secret detention following his return from the United States.

Mr Zhou is a permanent US resident, relatives said, and his case could stoke contention between Washington and Beijing.

He was charged with fraud by police in his home city of Suining in southwest Sichuan province, said his brother, Zhou Lin, who spoke by telephone. Zhou Lin said his family received the written arrest notice yesterday morning.

Zhou Lin said he did not know the specifics behind the accusation, nor when his brother could have committed fraud in China, given his long residence in the US.

Zhou Yongjun's partner, Zhang Yuewei, called the charge unfounded. "He's been under secret detention for a long time, since he tried to enter China last year," said Ms Zhang, speaking from California, where the couple live.

"At first he was accused of spying and political crimes, but now they have switched to this financial fraud accusation."

Calls to the Suining Public Security Bureau either went unanswered or officers said they did not know of the case. The US Embassy in Beijing had no immediate comment.

Mr Zhou, 41, was a law student who helped organize the mass movement demanding democratic reform that erupted on Chinese streets in 1989. He was on Tiananmen Square on June 4 that year as armed troops moved in to quash the protests, according to accounts from the time. Hundreds died in the crackdown.

After years in detention, Mr Zhou fled to the US in 1993. When he tried to return to China in 1998, he was sentenced to three years of "re-education through labour" and returned to the US in 2002.

When he again tried to enter mainland China in September last year, he was detained when he tried to cross over from Hong Kong said his family. He recently moved to Suining.

"He wanted to see his father, who is old and sick, but I didn't want him to go," said Ms Zhang.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.