China artist Ai WeiWei released

Renowned artist Ai Weiwei, the most high-profile target of a sweeping crackdown on activists in China, has returned home after nearly three months in detention.

Looking tired and thinner, he said the conditions of his release meant he could not talk more.

The official Xinhua News Agency said Ai confessed to tax evasion, accusations his family had long denied and which activists had denounced as a false premise for detaining him. He has spoken out strongly against the ruling Communist Party, and his family and supporters say he was being punished for speaking out about the communist leadership and social problems.

Ai, who had been taken away on April 3, walked through the gate of his suburban home studio shortly after 11pm on Wednesday (local time)  with his mother and wife. He said his health was fine and thanked reporters for their support outside his studio, but said he could not speak further.

"I'm sorry I can't (talk), I am on probation, please understand," Ai said, speaking in English.

The conditions appeared to extend also to Ai's family, although his mother told reporters she was relieved to see him again. "I'm so happy that my son is back," Gao Ying said.

The outspoken artist's detention had sparked an international outcry, with the United States and other countries saying it was a sign of China's deteriorating human rights situation.

That international condemnation, along with Ai's party connections as the son of one of China's most famous modern poets, had convinced authorities to strike a deal with Ai on his release, said Jerome Cohen, a top expert on Chinese law at New York University.

"As often happens with sensitive cases, it was too hot to handle and they had to find a way out," Cohen said by phone from New York City.

He said Ai was most likely released on a form of bail that restricts suspects' movements to their home city for one year. However, authorities can reopen the case at any time, meaning Ai faces the ever-present threat of being detained again on the same accusations.

Despite that, Cohen said Ai's release under those terms was probably the best outcome that could be expected, given the degree to which he had angered those in power.

"It's quite a step back for the regime. It demonstrates the utility of large amounts of international attention, plus international connections that had been sufficient to keep him out of jail before," he said.

Ai's release might also have been a face-saving move, coming just days before Chinese Premier Wen Jiabao was due to travel to Hungary, Britain and Germany, countries where supporters of the artist have been vocal in their condemnation of his detention.

German Foreign Minister Guido Westerwelle was cautiously optimistic about Ai's release.

"That would be a big relief for the artist and his family, even though the reported circumstances of his release on bail continue to appear depressing," Westerwelle said in a written statement.

State Department deputy spokesman Mark Toner told a news conference the US had yet to confirm the media reports of Ai's release but that Washington would welcome it.

"It's always a good thing when an individual who is only in prison for exercising his internationally recognized human rights is released," Toner said.

Several of Ai's work colleagues have also been detained, but there was no immediate word on their fate.