WASHINGTON (AFP) — The family of Chinese rights lawyer Gao Zhisheng, who has been tipped for a Nobel Peace Prize and disappeared weeks ago, has defected to the United States, according to supporters.

The wife and two children of Gao -- who said he was tortured after drawing international attention to China's rights abuses -- sneaked out by foot into Thailand and arrived in the United States on Wednesday, rights groups said.

"It was extraordinarily difficult to get us out of China. The friends who helped us escape took enormous pains, some even risking their own lives," Gao's wife, Geng He, told Radio Free Asia's Mandarin service Thursday.

The defection came during a visit to Washington by Chinese Foreign Minister Yang Jiechi, who has warned President Barack Obama's administration to "stop meddling" in Beijing's affairs over human rights.

Gao, once a prominent lawyer and communist party member, has been an outspoken defender of people seeking redress from the government including coal miners, underground Christians and the banned Falun Gong spiritual movement.

After he wrote an open letter to the US Congress in 2007, Gao said he was subjected to several weeks of torture including suffering electric shocks to his genitals and having his eyes burned by cigarettes.

In its latest annual human rights report, the US State Department said Gao's whereabouts were unknown. Gao was considered among the front-runners last year for the Nobel Peace Prize.

New York-based Human Rights in China said Gao was again taken away by state security from his home village in central Shaanxi province on February 4 -- about a month after his family fled -- and has not been heard from since.

ChinaAid, a US-based group assisting Christians in communist China, said it helped the family fly to Los Angeles and then to Phoenix, where they are now staying.

Geng told Radio Free Asia that her daughter, 15, and son, 5, were under virtual house arrest in Beijing. The girl attempted suicide several times out of desperation as she was unable to attend school, Geng said.

"I had no place to turn. So I fled with my children," she said. The US-based radio service said the family was seeking asylum.

Geng said Gao could not defect as he was under constant police surveillance. She said the family managed to evade detection by traveling by train and then crossing into Thailand on foot.

"We walked day and night. It was extremely hard," Geng told Radio Free Asia.

She said that members of the Falun Gong helped her escape.

Her husband wrote a rare open letter in 2005 accusing Chinese authorities of persecution including torture of members of the movement.

Falun Gong, which combines meditation with Buddhist-inspired teachings, was banned in mid-1999 by Beijing as an "evil cult." China has a long history of folk religious movements challenging the central government's authority.

Gao, a Christian, resigned his membership in the Chinese Communist Party in 2005 to protest the repression of Falun Gong.

"It was the proudest day of my life," he once told a Chinese journalist in an interview.

Gao could have enjoyed a more comfortable life. After he opened an office in Beijing in 2000, the justice ministry designated him as one of the country's top 10 lawyers due to his service to the poor.

But Gao said he was inspired to defend the downtrodden due to his own background.

Born to peasants in Shaanxi, one of China's poorest provinces, Gao lost his father at age 10, forcing his mother to care by herself for seven children.

"I know how poor people live and that's why I know what I'm doing," he said in a 2005 interview with a Chinese journalist.

In his 2007 letter to the US Congress, Gao hit on one of the most sensitive points for China, urging the United States to oppose the Beijing Olympics the following year because of human rights violations.

In the letter, Gao said he had twice read the debates of James Madison, the fourth president of the United States, during the 1787 Philadelphia convention that drafted the constitution.

"(I) admired the freedom and democratic constitution which China has not been able to enjoy," he wrote.