China released human rights lawyer Teng Biao after ten weeks in custody but a second lawyer has disappeared, rights groups told AFP Saturday, amid an ongoing crackdown on dissent. Advocacy group China Aid said Teng returned home at 3:30 pm (0730 GMT) on Friday but also stated that Li Fangping disappeared around 5:00 pm after leaving the office building of an AIDS victims group in Beijing. Teng Biao\'s wife confirmed to AFP that her husband had returned home but said \"it is not convenient to speak now\". \"It\'s a relief that Teng Biao has been released after almost 70 days of unlawful confinement at the hands of China\'s security forces,\" said Phelim Kine, Asia researcher at New York-based Human Rights Watch (HRW). In February, Teng and other lawyers involved in defending Chen Guangcheng, an activist who has spoken out about forced abortions in China, were arrested, interrogated and beaten by police following a meeting in Beijing. HRW also named Li as the latest lawyer to disappear since China launched a blitz on government critics following calls for protests to match those rocking the Arab world. The developments came after the latest human rights dialogue between the United States and China in Beijing broke off with the two countries at loggerheads after talks failed to produce any progress. HRW\'s Kine said Li\'s disappearance \"suggests that security forces are conducting a carefully planned assault on outspoken human rights defenders in a calculated effort to eviscerate China\'s rights defence movement.\" Renee Xia, from Chinese Human Rights Defenders, told AFP that \"nobody has any idea why (Li is being detained) now\", but added \"it is not a surprise, he is a very active human rights lawyer\". China Aid said Teng and Li are both active members of the Chinese Christian Rights Defense Association, which has come to prominence since repeated arrests of Christians in recent months. China\'s communist government has long frowned on religion and imposes controls on faith by requiring groups to register for government approval to gather, despite an official policy stipulating religious freedom. On April 10, nearly 170 church followers were rounded up by police after trying to hold an outdoor service in western Beijing. Nearly 50 were detained a week later and a further 30 were arrested on April 24 for trying to hold an Easter service in defiance of the officially atheist government. Bob Fu, president of China Aid, welcomed Teng\'s release but warned \"China cannot continue to play this game by letting one go and taking one in if China wants to be seen as a responsible international partner.\" US Assistant Secretary of State Michael Posner on Thursday accused China of \"serious backsliding\" on human rights after the two-day US-China Human Rights Dialogue concluded in the Chinese capital. Chinese authorities have launched their toughest campaign against government critics in years after anonymous online appeals emerged in February calling for weekly protests to emulate those inthe Arab world. Scores of Chinese activists and rights lawyers have been rounded up since the emergence of the \"Jasmine\" campaign, which has gone largely unheeded. The US State Department had made clear before the latest dialogue that it would zero in on China\'s clampdown and a \"negative trend of forced disappearances, extra-legal detentions, and arrests and convictions\". Human rights groups had urged the Americans to step up pressure in the dialogue, which has been criticised as a toothless talking shop that had achieved nothing so far in pressuring China to improve its rights record. But there was no breakthrough and China on Thursday repeated its insistence that its handling of dissent was its own business. Posner said the US side raised sensitive issues such as restrictions on religious groups, China\'s handling of restive minorities such as Tibetans and Muslim Uighurs, and the detentions of scores of rights lawyers and activists. These included the case of Ai Weiwei, a prominent artist and staunch critic of the Communist Party whose disappearance into police custody in early April sparked criticism from around the world.