Chinese police on Saturday released leading dissident Xu Wenli after holding him overnight and warning him "not to cross the line," Xu said.

Speaking by telephone from his Beijing home, Xu, 54, said police had not accused him of any wrong-doing. He has written a string of letters to authorities urging the creation of a human rights watchdog group and the release of a fellow dissident sentenced to three years in a labor camp last month."They clearly warned me not to cross the line, for instance telling me not to publish my materials without first seeking approval," Xu said. He said he had sought approval but had not received any reply.

Police on Friday raided his home, taking him away and carting off his computer, letters and photographs, Xu said. Officials at the Beijing Public Security Bureau declined comment on the case.

Xu was a leading member of the 1978-79 Democracy Wall movement along with activist Wei Jingsheng, who went into exile in the United States last November after being released from jail on medical parole.

Last month Xu wrote an open letter to authorities condemning the sentencing of Shanghai-based dissident Yang Qinheng because of a letter he wrote to parliament about unemployment.