Chinese authorities on Tuesday prevented relatives of prominent dissident and human rights lawyer Gao Zhisheng from visiting him in prison, his brother said.

Gao, who has defended some of China's most vulnerable people including Christians and coal miners, was arrested in February 2009 and has been held largely incommunicado by authorities except for a brief release in March 2010.

Earlier this month his brother Gao Zhiyi said he had received a letter from a Beijing court to say the lawyer was being held in a jail in the remote northwestern region of Xinjiang.

On Tuesday his father, elder brother and two sisters went to the prison to visit the activist, whose detention has generated international condemnation.

"We weren't allowed to see him. The prison told us we have to wait for three months and apply again," Gao Zhiyi told AFP by phone. "We were all refused. You can imagine how my father feels."

Prison authorities said the activist was undergoing a three-month period of "education" and apparently was not allowed visits during this time, the brother said.

Gao's wife, Geng He, fled to the United States with her two children in 2009 after suffering what they said was constant police harassment at their Beijing home.

The official Xinhua news agency said last month that Gao had been sent back to prison after a court ruled he had violated the terms of his probation, though it gave no date or details of the alleged violation.

The United States, the European Union and the United Nations all responded by calling on Beijing to release him.

Calls to the jail went unanswered Tuesday, but Beijing-based lawyer Mo Shaoping said Gao's family had a right to visit the activist in accordance with regulations on prison visits.

Gao's brother had hoped to discuss a possible retrial of the 2006 case, Mo said.

"Gao Zhisheng's brother and his wife have asked me to take up the task of seeking a retrial for Gao Zhisheng," Mo, who has represented numerous Chinese dissidents, told AFP.

"I told them they should go to the prison and get the views of Gao Zhisheng and if he agrees to a retrial, then of course I would take up the work and begin legal procedures."

Campaign launched to find disappeared Chinese bishops
Vatican City (AFP) Jan 10, 2012 - A Catholic agency on Tuesday launched a campaign to raise awareness on the fate of two Chinese bishops who disappeared over a decade ago, criticising the Vatican for its kid-glove approach to China.

The two men -- Su Zhimin and Shi Enxiang, who were both Catholic bishops in Hebei province in northeast China -- have been missing ever since they were arrested and sent to forced labour camps in 1997 and 2001 respectively.

The Asia News agency, which is part of the independent Pontifical Institute for Foreign Missions in Rome, would now be aged 80 and 90 if they are alive.

Su, the former bishop of Baoding, was apparently spotted in 2003 in a hospital under police guard but he has not been seen since. There has been no news as to the fate of Shi, the former bishop of Yixian, after his arrest.

"The Vatican's gentle approach in contact with the Chinese authorities has not managed to free these bishops and the dozens of clandestine priest who are still in the camps," said Bernardo Cervellera, director of Asia News.

Cervellera called on the Vatican to "set their liberation as a condition for relaunching any kind of dialogue" with China.

The Vatican has very difficult relations with China, which only recognises a state-sanctioned Catholic Church.

"These two people are symbolic of the refusal of any compromise with a regime that continues to deny true freedom of religion to its citizens," said Regis Anouil from the "Eglises d'Asie" missionary agency in Paris.