China has freed a prominent dissident from prison for medical reasons and he is on his way to the United States. The release comes a week after a senior U.S. human rights envoy visited China. An American human rights activist said China released Xu Wenli early from his 13 year jail term Tuesday and put him on a flight to the United States.

John Kamm, who has helped negotiate the release of several Chinese political prisoners, told reporters in Beijing that the Chinese government had authorized him to make the announcement.

Mr. Xu, who suffers from hepatitis B, was arrested in 1998 after joining with other activists to organize the China Democracy Party, which opposed the Chinese government. Beijing crushed the party soon afterwards and sent dozens of its members to jail on charges of subversion.

Mr. Xu's release comes just a week after Assistant Secretary of State Lorne Craner conducted high-level human rights talks with Chinese officials here. Mr. Craner said he presented a list of political prisoners to Beijing, and highlighted Mr. Xu as a priority case.

China often frees prominent prisoners as a gesture of good will surrounding visits by senior American officials or Sino-American summits. Mr. Craner told reporters following his visit here that Beijing appeared to be more serious about improving its human rights record, and to cultivate better ties with the United States.

Mr. Xu was first arrested for advocating greater political freedom during the 1979 Democracy Wall movement. Before his current prison term, he served time on charges of counterrevolution.