Beijing  - The wife and children of leading Chinese human rights lawyer Gao Zhisheng have escaped from close police surveillance and travelled via Thailand to the United States, US-funded Radio Free Asia reported Friday.

Gao's wife, Geng He; their 15-year-old daughter; and 5-year-old son walked into Thailand after fleeing from virtual house arrest in Beijing and crossing a border in southern China, the broadcaster quoted Geng as saying.

"I left China because my family had been under tight surveillance for a long time," she said.

"We experienced in our careers and daily life great hardship and difficulty," Geng added.

Radio Free Asia said Geng and her children arrived in the United States Wednesday to seek asylum.

Her daughter "tried to commit suicide several times" because she was unable to attend school, she told the broadcaster.

The report did not say how the family crossed into Thailand, which has no border with China but is accessible via Laos or Myanmar.

It said the trio left China on January 9 and arrived in Thailand on January 16, travelling to the United States Tuesday.

Geng said they left Beijing by train but that Gao could not travel with them because he was unable to shake off his tighter surveillance by state security police.

She and her children eluded their surveillance team with the help of friends who were members of the banned Falun Gong spiritual movement, whose legal rights Gao has supported.

"It was extraordinarily difficult to get us out of China," Geng said.

"The friends who helped us escape took enormous pains, some even risking their own lives," she said.

Gao, 44, is a self-taught lawyer who built a reputation as a stout defender of people who suffered injustices at the hands of Chinese government officials and the police.

He was not afraid to take on the most sensitive cases despite threats, violence and imprisonment by the authorities under China's ruling Communist Party.

The government closed his Beijing-based Shengzhi law firm in 2005 after he called via the internet for an end to the persecution of Falun Gong members who were sent to a re-education camp.

It tried to silence him by passing a three-year suspended prison sentence for subversion at a closed trial in December 2006.

The court convicted him of publishing seditious articles on foreign websites, including open letters on Chinese President Hu Jintao and Prime Minister Wen Jiabao as well as an article entitled The Regime That Never Stopped Killing People.

In recent years, Gao often called China's one-party rulers "barbaric" and likened them to "Mafia bosses."

He had campaigned on behalf of protesting farmers, dissidents, Christians, AIDS activists and fellow rights lawyers.

Gao also came into conflict with police and state security officers through public complaints about constant surveillance and harassment.

An English translation of his book, A China More Just, was published in 2007.

Known to friends as fearless, Gao as a young man served in the People's Liberation Army in China's central Asian region of Xinjiang.

A few years after leaving the army, he began studying law in the early 1990s and worked as a lawyer in Xinjiang until he moved to Beijing in 2000. (dpa)