BEIRUT — The family of an American journalist says he went missing in Syria more than one month ago while covering the civil war there.

A statement released online Wednesday by the family of James Foley said he was kidnapped in northwest Syria by unknown gunmen on Thanksgiving day.

The statement appealed to those holding Foley to contact the family “so we can work together toward his release.”

Foley, 39, has worked in a number of conflict zones around the Middle East, including Syria, Libya and Iraq.

He was contributing videos to Agence France-Press while in Syria.

The news agency quoted its chairman, Emmanuel Hoog, as saying it was doing all it could to secure Foley’s release.

“He is a professional journalist who is absolutely neutral in this conflict,” Hoog said.