Beijing: Human rights groups and Western officials welcomed the release on bail of outspoken Chinese artist Ai Weiwei but voiced dismay about the conditions and urged Beijing to free other activists.
The 54-year-old Ai, who was detained in early April, was unexpectedly freed late Wednesday because of "his good attitude in confessing" to tax evasion, his willingness to repay taxes he owes, and on medical grounds, state media said.
His detention -- which came during a major government crackdown on activists launched in February -- sparked an international outcry, with Western governments and rights groups repeatedly calling for his immediate release.
"I`m fine. I`m very happy to be free and I`m very happy to be back with my family," Ai said early Thursday. He later said he had left his home in an artist district on the outskirts of Beijing with his family.
Calling his release a "relief for his family, friends and supporters", Human Rights Watch nevertheless pointed out that "troubling unanswered questions about his arrest, detention and conditions of release" remain.
The New York-based group said it was "concerned about the political nature of his arrest, the conditions under which the police may have extracted a `confession` from him, and possible restrictions on freedoms he faces".
It also called for the release of other activists who have disappeared into police detention since mid-February when Beijing -- nervous about online calls for protests echoing those in the Arab world -- clamped down on dissent.
"International pressure apparently prodded the Chinese government to conclude that the cost-benefit ratio of continuing to detain Ai Weiwei wasn`t worth it," said HRW`s Asia advocacy director Sophie Richardson.
"The international community should maintain that same pressure for the release of the many other innocent victims of the Chinese government`s current wave of repression."
Amnesty International also hit out at Beijing, saying Ai`s long detention without charge "violated China`s own legal process", and urged the world to push for the release of other dissidents.
Ai should be granted "full liberty, and not be held in illegal house arrest as has been the pattern with so many others recently released from arbitrary detention," Amnesty`s Asia-Pacific Deputy Director Catherine Baber said.
"It is vital that the international outcry over Ai Weiwei be extended to those activists still languishing in secret detention or charged with inciting subversion."
Paris-based media watchdog Reporters without Borders noted that Ai`s release did not necessarily mean "the end of his problems", saying he could still be convicted and face "an exorbitant fine".
The son of a poet revered by China`s early Communist leaders, Ai helped design the Bird`s Nest Olympic Stadium for the 2008 Beijing Olympic Games, but has since become a thorn in the government`s side.
He has angered authorities with his involvement in a number of sensitive activist campaigns and his relentless criticism of the ruling Communist Party.
He probed the collapse of schools in the 2008 Sichuan earthquake, looked into a Shanghai high-rise fire last November that killed dozens, and says police beat him when he tried to testify on behalf of another activist in 2009.
Ai`s release came just before Chinese Premier Wen Jiabao sets off Friday on a European tour, with stops in Hungary, Britain and Germany.
London and Berlin have been especially vocal about the case, as have European Union officials.
German Chancellor Angela Merkel said on Wednesday that Ai`s release "can only be a first step", calling for the charges against him to be clearly explained.
"Now, the accusations that have been made against (him) must be explained in a transparent manner and in conformity with the rule of law," she said in a statement released by her office.
European Parliament president Jerzy Buzek insisted that Ai`s arrest "was both unjustifiable and unacceptable".
The US State Department declined comment until US diplomats could verify his release.
Ai joined Merkel, Facebook founder Mark Zuckerberg, British actor Colin Firth and Myanmar`s democracy icon Aung San Suu Kyi this year in Time magazine`s annual list of the world`s 100 most influential people.