Gao Zhisheng gestures during an interview at a tea house in Beijing in this Feb. 24, 2006 file photo. Gao, a Chinese lawyer convicted of subversion has again been detained after writing to U.S. lawmakers asking them to help expose what he called an "ongoing human rights disaster in China," an activist friend said Tuesday, Sept. 25, 2007. (AP Photo/Ng Han Guan, File)

BEIJING (AP) — A Chinese lawyer convicted of subversion has again been detained after writing to U.S. lawmakers asking them to help expose what he called an "ongoing human rights disaster in China," an activist friend said Tuesday.

Gao Zhisheng was taken from his Beijing apartment by plainclothes police on Saturday night, activist Hu Jia said, citing information from Gao's relatives. The relatives did not know where Gao was taken or whether he faced new charges, Hu said.

On Friday, an open letter by Gao to the U.S. Congress was released by the Falun Gong spiritual group. It said Congress could help bring change to China by supporting free media outlets and the opening up of the Internet.

Hu said Gao told him five days before his detention that police had threatened him with jail if he released any open letters or statements.

"More and more Chinese people are speaking out against the coming Olympic Games in China, which they often refer to as 'the bloody Olympics' and 'the handcuff Olympics,'" Gao said, according to the letter signed Sept. 12.

Under the terms of his parole, Gao has been denied political rights, including the right to free speech and the ability to gather or protest. Such letters violate that order.

Hu said Gao has been repeatedly detained for days or weeks at a time over the past nine months, and his latest detention was likely related to an overall tightening of controls ahead of a sensitive political congress next month.

The Communist Party congress, held every five years, will set the agenda for the party and country for the next five years, and will likely include a reshuffling of some top leaders. It will also mark a renewal of party leader Hu Jintao's five-year tenure.

Gao became a prominent critic of China's civil rights lapses in 2002-2006. He took on cases involving property-rights violations, the banned Falun Gong group and religious persecution.

He was arrested in August 2006 on subversion charges based on nine articles posted on Web sites abroad, the official Xinhua News Agency reported then. He was convicted and later placed under house arrest.