A Chinese human rights lawyer whose secret detention and alleged torture by Communist authorities prompted an international outcry was released Thursday after a three-year jail sentence, his wife and a relative said.

Gao Zhisheng, who defended some of China's most vulnerable people including Christians and coal miners, has been held largely incommunicado since 2009.

"He is out (of jail), but he has not returned home -- he's at his father-in-law's house in Urumqi," a close relative of Gao told AFP by telephone, referring to the capital of the far-western region of Xinjiang where the lawyer had been serving his sentence.

The relative added that Gao's health was "normal, quite good", but asked not to be named because of the sensitivity of the matter.

It was not clear whether Gao, 50, will still be subject to some form of house arrest as he has been previously.

His wife Geng He, who now lives in the United States, told AFP she had spoken to Gao following his release but was worried that he had been "tortured" in jail.

"Five of his upper teeth are very loose, and three lower ones are bad, my sister said he has to break bread into little pieces before he can eat it."

The lawyer's voice sounded "very flat," she said, adding that her phone call was cut off by the entrance of what she suspected were security agents.

Beijing-based activist Hu Jia said a relative of Gao told him the lawyer would stay in Urumqi to receive treatment because his "teeth are in a bad condition" before returning to his hometown in the northern province of Shaanxi.

Gao was convicted of "subversion of state power" in 2006, and given a suspended sentence of three years in prison. He was immediately placed under house arrest and put on probation for five years.

In 2009 he was detained by Chinese security officers and held in secret for more than a year, with his family not told of his whereabouts.

After returning home for a month in March 2010, he went missing again. State media said in 2011 that he had been sent back to jail for three years after a Beijing court said he had violated his probation terms.

The decision was criticised by the United Nations, the United States and the European Union, which repeatedly called for Gao's release, and by rights groups such as Amnesty International.

- 'Beaten all over' -

China's ruling Communist party retains tight control over the courts, and authorities often detain outspoken lawyers.

Beijing says that decades of economic growth have improved the country's human rights situation.

Gao was born into a poor family but became a successful lawyer, and in the 1990s won several high-profile cases for clients who sued over abuses by officials.

On behalf of clients he won lawsuits against local authorities over the forced implementation of China's "one child policy," and illegal seizures of farming land.

He was named "one of China's top 10 lawyers" in a 2001 event co-organised by a state-run broadcaster and China's ministry of justice.

But his troubles began around 10 years ago, when he renounced his Communist Party membership and openly called for an end to a crackdown on the banned Falungong spiritual group.

He had provided legal assistance to members of the group who had been sent to labour camps.

He openly accused police of torture, including electric shocks to his genitals and cigarette burns to his eyes.

"Four men with electric shock prods began beating my head and all over my body," during a three-day detention in 2007, he wrote in an account obtained by US-based Human Rights in China.

"I saw my body was in a horrifying condition. Not a single square centimetre of my skin was normal. It was bruised and damaged over every part," he said of a 50-day detention later that year.

- 'Still worried' -

Advocacy groups say that a campaign against rights lawyers has intensified under China's President Xi Jinping, who came to power in 2012.

Prominent human rights lawyer Pu Zhiqiang was arrested in May and later charged with "picking quarrels and causing trouble", prompting an outcry.

The United States welcomed news of Gao's freeing but called on Beijing to "release all prisoners of conscience".

"We also urge Chinese authorities to allow him to leave China to be reunited with his family in the United States if he so chooses," State Department spokeswoman Marie Harf told reporters.

After release from prison Gao will face a period of "deprivation of political rights," during which he could be barred from speaking to the media.

"We will have to monitor the situation, as it's still unclear what the authorities' possible measures against him will be," said Maya Wang, a researcher for Human Rights Watch.

"Given the fact that in the past he has had long stretches of time during which he was forcibly disappeared, we are still worried and concerned about what will happen to him when he gets home," she added.

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