Chinese police have begun investigating the detained artist, Ai Weiwei, for suspected economic crimes.
China’s state news agency, Xinhua, reported the investigation but gave no other details.
It is the first official update on Ai Weiwei since he was detained by officials at Beijing airport on Sunday.
Ai Weiwei, who co-designed the Beijing Olympic stadium known as the “Bird’s Nest”, is often described as China’s most famous contemporary artist.
He is also one of the Chinese government’s fiercest critics, complaining about a lack of basic rights and freedoms – often incorporating these political themes into his work.
Xinhua’s one-line English-language report on the investigation later appeared to have been removed from its website. Internet links to the story returned an error message.
The BBC’s Jo Floto in Beijing says Mr Ai, the son of a prominent communist, had appeared to enjoy a degree of protection.
In the last couple of months, dozens of activists have ended up in custody or house arrest, none of them as open in their criticism as Mr Ai.
The news that he is being investigated for economic crimes may signal that China’s authorities will seek to characterise him as a common criminal, rather than a political prisoner, our correspondent says.
On Wednesday a Chinese state-run newspaper, The Global Times, described him as a maverick who took part in legally ambiguous activities.
Police later seized computers and money at his home and his wife, Lu Qing, told reporters the raid involved more than 40 policemen going in and out of their home.
She says she has heard nothing since.
“I am waiting for news,” she said. “I so far have no information from the authorities about the fate of Ai Weiwei.”
“He felt a premonition that he would be detained,” she added.
She is also concerned for his health, saying the 53-year old artist takes medicine for a range of illnesses.
Foreign governments have called for Ai Weiwei’s immediate release.
The US Ambassador Jon Huntsman mentioned the artist among other activists who “challenge the Chinese government to serve the public in all cases and at all times”.
Human rights groups say China’s current crackdown on dissent is a response to protests in the Middle East and North Africa.
Human Rights Watch said up to 25 lawyers, activists and bloggers had been either detained, arrested or had disappeared. Dozens more had been subjected to harassment, it said.
Ai Weiwei currently has an exhibition at the Tate Modern gallery in London, displaying 100 million porcelain objects that look like sunflower seeds.
This article is from the BBC News website. © British Broadcasting Corporation, The BBC is not responsible for the content of external internet sites.