BEIJING — An award-winning photographer known for capturing images of China's environmental damage and the lives of the country's dispossessed has vanished.

Lu Guang, a U.S. green card holder who splits his time between New York and Beijing, hasn't been heard from since Nov. 3, according to his wife.

Lu had been meeting with photographers who had invited him to Urumqi, the capital of China's remote Xinjiang province.

In a phone interview with NBC News, Lu’s wife, Xu Xiaoli, said was initially not very concerned when he failed to get in touch. However, when he failed to meet a friend in Sichuan province on Nov. 5, Xu suspected something was wrong.

“The authorities haven’t informed me of his whereabouts,” she said from New York. “More than 20 days and no word from him. The longer I wait the more worried I am.”

Xu tried reaching officials in Xinjiang but was unable to find anyone able or willing to help her. Xu then contacted the wife of the photographer who had invited Lu to visit. She said they were both taken away by state security.

“I don’t know whether this is because of his work,” Xu said. “I don’t know why he was detained. He only went there to have a professional exchange with other photographers.”