Updated

A United Nations representative has pressed China to investigate the fate of prominent human rights campaigner Jiang Tianyong, who disappeared two weeks ago and is believed by friends to be held by state security agents.

Philip Alston, the U.N. special rapporteur on extreme poverty and human rights, said Tuesday that he is concerned Jiang's disappearance was "reprisal" for a meeting between the two in August.

Jiang has been detained and beaten by police as part of his past human rights work involving some of China's most sensitive cases. He recently helped publicize the plight of nearly two dozen lawyers arrested as part of a sweeping 2015 crackdown.

Friends and family say authorities in Beijing, Jiang's hometown of Zhengzhou and Changsha, where Jiang was last seen, have refused to investigate.