"Religious persecution is a daily reality in China," said Release CEO Andy Dipper. "The Chinese people need to be told the truth - and gatekeepers to the Internet Microsoft and Yahoo have a duty to let the truth be told."
The message came at a conference in London last week to raise awareness of the plight of persecuted Christians in China. The joint conference was held by human rights advocates Christian Solidarity Worldwide and Release International.
The conference highlighted the plight of human rights lawyer, Gao Zhisheng, who disappeared more than 400 days ago, after defending leaders of the persecuted house church and practitioners of the banned movement Falun Gong.
Addressing the conference was human rights campaigner, Bob Fu, a former leader of the Tiananmen Square student protest in 1989. He called on China to release immediately Nobel Peace Prize nominee Gao Zhisheng, whom he said had been tortured severely.
"When the authorities arrested Gao previously in 2005 they tortured him in ways that cannot be described," said Fu, head of ChinaAid Association. "If he is still alive, they are almost certainly torturing him again. The aim is to break his spirit and to scare off other human rights campaigners."
Fu was one of the last men to speak to Gao Zhisheng before he was hauled away by the Chinese authorities 400 days ago.
"We do not know for sure now whether Gao is dead or alive. It's possible the authorities have disfigured or crippled him and would now be embarrassed to let him be seen," he said.
"We call on China to let the world know whether he is still alive and, if so, release Gao immediately."
Applauding Google's decision to no longer allow China to censor its web browser, Fu extended a challenge to Yahoo and Microsoft to follow suit.
He said: "My message to Bill Gates and Yahoo is do the right thing. Don't sell your conscience. Don't give in to censorship."
Dipper added: "We call on the international community to continue to bring pressure to bear on China to allow religious freedom and freedom of speech. We hope Microsoft and Yahoo will indeed do the right thing and stand up for freedom."
Fu later briefed parliamentarians in the House of Lords on the continuing abuse of human rights in China.
ChinaAid reports persecution increased by almost 20 per cent in 2009. Some of the harshest persecution was suffered by the House Church movement, churches that refuse to register with the government and submit to state control and restrictions. ChinaAid recorded almost 3,000 cases of individual persecution, with a growing trend towards abuse and intimidation, rather than prosecution.