BEIJING — An activist who has spent the last several years documenting labor protests across China has been detained by the authorities since mid-June, his friends said on Monday.

Lu Yuyu was taken into custody by the police on June 16 in the southwestern town of Dali, where he lives, said Xu Hui, a writer who has had regular online contact with him.

Dali, a mountainous tourist area in Yunnan province, has in recent years drawn a growing number of Chinese fleeing hectic, polluted urban centers. Xu also lives in Dali and said he had twice visited the detention center where Lu is being held but had not been allowed to see him.

The authorities are accusing Lu and his girlfriend, Li Tingyu, of “picking quarrels and provoking trouble,’’ said Xu and another friend, Wei Xiaobin. Li has also been documenting worker unrest.

That accusation has been used with increasing frequency by the police in China to silence dissent. In Sichuan province, another liberal activist, Chen Yunfei, who advocates for the remembrance of the 1989 Tiananmen Square massacre, is expected to stand trial on the charge on Thursday.

New York Times