BEIJING — Chinese legal authorities released dissident artist Ai Weiwei on Wednesday after a three-month detention, apparently ending a prosecution that had become a focal point of criticism of China’s eroding human rights record.

“I’m released, I’m home, I’m fine,” Ai said in English after being reached on his cellphone shortly before 12:30 a.m. Thursday. “In legal terms, I’m — how do you say? — on bail. So I cannot give any interviews. But I’m fine.”

Photographs of Ai taken as he arrived after 11 p.m. Wednesday at his studio in the Caochangdi arts district of northeast Beijing showed him smiling, wearing a blue T-shirt, and with his trademark bushy beard streaked with gray. The shirt hung loosely on him, his girth reduced during his time in custody.

The release of Ai, 54, who is widely known and admired outside of China, appeared to be a rare example in recent years of Beijing bowing to international pressure on human rights, though the terms of his release may silence him for months or even years, giving hard-liners here at least a partial victory. Ai was the most prominent of hundreds of people detained since China intensified a broad crackdown on critics of the government in February, when anonymous calls for mass protests modeled after the revolutions in the Middle East percolated on the Chinese Internet.

China’s move to douse any flicker of dissent was the harshest in years outside of the restive ethnic regions in the far west, and the vast majority of those detained in the crackdown were, like Ai, held in secret locations for weeks with no legal justification.

Chinese officials announced in May that authorities were investigating Ai on suspicion of tax evasion, after police officers took him from the main Beijing airport April 3 as Ai prepared to board a flight to Hong Kong. Ai’s supporters said the tax inquiry was a pretext to silence one of the most vocal critics of the Chinese Communist Party.

Ai is presumed to be well connected because he is the son of Ai Qing, one of the most beloved poets of modern China. His detention was nearly certain to have been approved by top Chinese leaders, and it is unclear what kinds of discussions took place within elite political circles that ultimately led to his release.

But China came under unusually heavy pressure from all corners of the globe, not only from standard diplomatic channels but also from prominent people like Mayor Michael Bloomberg of New York, who harangued China in May at a Manhattan opening of an outdoor sculpture exhibition by Ai, and Anish Kapoor, a leading sculptor in Britain who this month canceled a show planned for the National Museum of China in Beijing. Premier Wen Jiabao of China was scheduled to visit Britain and Germany starting Saturday, and he almost certainly would have encountered protests and condemnation, whether on the streets or in private meetings.

“Without the wave of international support for Ai and the popular expressions of dismay and disgust about the circumstances of his disappearance and detention, it’s highly unlikely the Chinese government would have released him,” Phelim Kine, an Asia researcher for Human Rights Watch, said in an email. “The public announcement of his release signals that the Chinese government has had to respond to this pressure and that the cost-benefit ratio of continuing to detain him was no longer tenable.”

Kine noted that less visible Chinese remain missing and “at high risk” of torture. Among them are Wen Tao, a former journalist and aide to Ai, and other of Ai’s associates, including Hu Mingfen, Liu Zhenggang and Zhang Jinsong.

Gao Ge, Ai’s sister, said in a telephone interview that Ai’s wife, Lu Qing, got a call Wednesday and was told to go to a police station in Beijing. “She didn’t know what would happen, and then the police said that Weiwei was free to go with her back home,” Gao said.

Ai got home before midnight, and his mother went to meet him.

“All I care about is that he’s home now,” Gao said.

Word of Ai’s release first emerged in a report posted online Wednesday night by Xinhua, the state news agency. It said in English that the Beijing police had released Ai on bail “because of his good attitude in confessing his crimes as well as a chronic disease he suffers from.”

Xinhua also quoted the police as saying that Ai had repeatedly said he was willing to pay the taxes he had evaded. The news agency reported authorities as saying that Beijing Fake Cultural Development Ltd., a company controlled by Ai, evaded “a huge amount of taxes and intentionally destroyed accounting documents.”

“Bail” is the shorthand commonly used as an English translation of the Chinese term “qubao houshen,” which means obtaining a guarantee pending trial. It generally means that prosecutors have decided to drop charges against a suspect on certain conditions, including good behavior, and to monitor him over a period of time during which charges could be reintroduced.

“This is a technique that the public security authorities sometimes use as a face-saving device to end controversial cases that are unwise or unnecessary for them to prosecute,” Jerome A. Cohen, a scholar of the Chinese legal system, said in an email. “Often in such cases, a compromise has been reached in negotiation with the suspect, as apparently it has been here.”

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Cohen said Ai’s release “is very good news and perhaps the very best outcome that could have been expected in the circumstances of this difficult case.”

Liu Xiaoyuan, Ai’s lawyer, said in a Twitter post that as long as the taxes were paid, Ai would probably remain free.

Ai’s family members have insisted that he is innocent of the accusations against him. Gao said in May that Ai was neither the legal representative nor chief executive of the company accused of evading taxes and should be freed. During his detention, the family also said Ai had been suffering from high blood pressure and diabetes, which required medication.

After Ai was detained April 3, authorities did not immediately detail any charges against him, and his incarceration was widely considered an attempt to silence a prominent critic while buying authorities time to decide on the legal grounds for prosecuting him.

He was held in an undisclosed location. On May 15, police officers took Ai’s wife, Lu, to see him. Gao said afterward that Lu had reported Ai seemed healthy and was being given access to medication. On May 20, a Xinhua report said the police had concluded Ai had evaded taxes and destroyed financial documents.

The police can legally continue to pursue the case for up to one year after “qubao houshen” releases. During that time, the suspect is allowed freedom of movement, but the police generally hold onto his travel documents.

Few dissidents who have been detained in recent years have been shown leniency. International pressure so far has not helped Liu Xiaobo, a writer who was sentenced in 2009 to an 11-year prison sentence on subversion charges. In October, he was awarded the Nobel Peace Prize, which he was not allowed to collect.