A Vietnamese artist who exhibited controversial works on land rights issues and death row inmates said he was briefly detained in the communist state intolerant of dissidence of any kind.
Thinh Nguyen was picked up outside his Hanoi home by several men who were not in uniform, along with one uniformed officer, and was driven to back to his house, which doubles as his studio.
The police forced their way in to the space and took him into custody at a nearby station for several hours, he told AFP after his release.
"They asked many questions concerning my work," said Thinh, who has produced art and films about social issues in Vietnam.
"I told them what they did today was not right, not in accordance with laws and I need my lawyer, and I refused to talk further," he said.
Thinh was bundled into a car but said the officers did not have an arrest warrant -- required according to Vietnam law in order to officially detain someone.
Before he was taken away he wrote to a friend saying "Security. Detained me," in text messages seen by AFP.
He was released late Friday evening, though said police confiscated two computers, several cameras and phones and other electronics and books.
A local police officer earlier told AFP he was not aware of the arrest, while the ministry of foreign affairs did not return a request for comment.
Human Rights Watch swiftly deplored Thinh's disappearance, saying it "shows the authorities' incredible intolerance for any sort of criticism," according to deputy Asia director Phil Robertson.
Thinh's work has irked officials in Vietnam, a one-party state where critics and activists are routinely jailed.
In a 2018 exhibition, he featured art by three death row prisoners he believes were wrongly accused.
The palm-size figurines of animals made from plastic bags were smuggled out by the inmates' relatives, and Thinh hoped the show would help raise awareness.
"These animals were the voices of the death row prisoners," he told AFP in a 2018 interview.
Thinh also exhibited photos of Hanoi residents who claimed they had been displaced from their land, and on Facebook posted about Hong Kong democracy protests and environmental issues.
All artworks must be approved by official censors before being displayed publicly in conservative Vietnam, where scores of critics are behind bars.
The country has seen an uptick in arrests for online posts since a controversial cybersecurity bill was passed in January, according to Amnesty International.