China said Thursday that dissident artist Ai Weiwei, who was released from jail a day earlier, remained under investigation and would be prohibited from leaving Beijing for at least the next year as a condition of his bail.

“Ai Weiwei is still under investigation,” Hong Lei, the Foreign Ministry spokesman, said at a regularly scheduled news briefing. “He is not allowed to leave his area of residence.”

Lei said that the “area of residence” referred to Beijing and that Ai was not being placed under house arrest.

The spokesman disputed the suggestion that international criticism played a role in the government’s decision to release the prominent artist after 81 days of detainment in an undisclosed location.

“The handling of Ai Weiwei’s case was the handling of a very common economic crime,” Hong said, according to agency transcripts of his remarks.

“China is a sovereign country under the rule of law,” he said. “We hope others respect its judicial sovereignty.”

China has accused Ai of evading taxes on a company he owns. His supporters, family members and attorneys have called the charges a pretext and say Ai was targeted for his increasing outspokenness at a time when the ruling Communist government is taking a heavy hand toward even the slightest dissent.

His arrest and detention subjected China to a firestorm of international criticism, including from the Obama administration and European governments.

Ai, meanwhile, made a brief appearance at the gate of his Beijing art studio where reporters had gathered. Ai declined to say much, other than to thank those who came and assure them he felt fine. He waved and said he was not able to speak publicly.

He appeared healthy, if somewhat slimmer than when he was seized by security officers at Beijing’s main airport on April 3. He wore a white T-shirt with his name in large letters, and his bushy beard seemed slightly grayer.

Before his disappearance into police custody — his wife was allowed one brief visit with him — Ai had emerged as a vocal anti-government critic who used his Twitter account, with tens of thousands of followers, to regularly chide the country’s authoritarian rulers.

Ai at times appeared to be pushing the envelope of permissible criticism, in one Twitter post in February seemingly mocking the Chinese authorities for being fearful of the kind of Middle East-style “jasmine” protests that toppled the regimes in Egypt and Tunisia.

Government concerns over the upheaval in the Arab world led to a crackdown of activists here, including bloggers and human rights lawyers. Human rights groups and others said that while they welcomed Ai’s release, they remained concerned about the fate of dozens of others still being held, many without formal charges and some under the same conditions as Ai, in undisclosed locations and without visits from family members or lawyers.

“At least 10 others who are less well known than Ai have been victims of enforced disappearances since mid-February,” the New York-based group Human Rights Watch said in a statement. “They remain incommunicado, their whereabouts unknown, and thus are at high risk of torture in custody.”

 Media outlets also reported Thursday that Ai’s cousin Zhang Jinsong, who worked closely with the artist, had also been released from detention.