Updated

Chinese state security officials have detained a journalist who recently disappeared after completing a documentary on labor camp abuses, the photographer's sister and close friend said Thursday.

The detention of Beijing-based video and photojournalist Du Bin, 41, is likely related to his work, said democracy activist Hu Jia, who said he's been a close friend of Du's for more than a decade. Du had recently completed a documentary exposing torture allegedly inflicted on detainees at a notorious labor camp in northeastern China as well as a 600-page book about the 1989 military crackdown on pro-democracy protesters in Beijing, published in Hong Kong.

Hu guessed from the timing of Du's detention late last month that authorities were being particularly sensitive during the anniversary of the June 4, 1989, Tiananmen crackdown.

"His work directly challenged the authorities. They are suppressing him to send a message to others," Hu said.

His detention comes amid a broader crackdown on China's small, beleaguered community of rights activists and dissidents launched under new Communist Party chief Xi Jinping. The campaign has dashed hopes that the new leadership might ease controls on civil society.

"I think that from a larger perspective, there has been no improvement in China's human rights situation since Xi Jinping took power, but in fact since the start of this year ... things have become even more conservative," Hu said.

Du Bin's sister Du Jirong said an officer at the local You'anmen police station verbally informed her on Thursday that her brother was being held at a detention center under state security orders. The sister said, however, that the family has not received any official notice about an investigation into Du Bin, who in the past has done freelance photo assignments for The New York Times.

A woman who answered the phone at the You'anmen police station confirmed that Du's family had been briefed but said she could not provide details of his case to people who are not his family members. The woman refused to give her name. Calls to the Fengtai District Detention Center, where Du's sister said he was being held, rang unanswered.

Hu and Du Jirong said Du Bin was last heard from on May 31 and that his apartment was searched by police the next day.

Chinese dissidents have decried what they see as a deterioration in the country's human rights record under Xi's leadership, pointing to detentions of activists calling for officials to declare their assets as well as an ideological offensive to undermine calls for constitutional governance. Activists slammed a Beijing court's ruling on Sunday to jail the brother-in-law of Nobel Peace Prize winner and democracy activist Liu Xiaobo for 11 years over a real estate dispute.