BEIRUT, Aug 31 (Reuters) - A Syrian court on Monday acquitted a prominent free-speech campaigner who was released from jail three weeks ago after being held for 3-1/2 years awaiting trial under anti-terrorism laws, his wife said.

Mazen Darwish was arrested in February 2012, nearly one year into the uprising against President Bashar al-Assad.

"Today, the court has added his case to a presidential pardon issued last year. They said it is included in the pardon so all charges have been cancelled," his wife, Yara Badr, told Reuters.

Darwish, 41, is founder of the Syrian Centre for Media and Freedom of Expression. He had been held on charges of spreading propaganda for terrorist acts, drawing protests from human rights groups and calls from the United States for his freedom.

When Darwish was released from prison on Aug. 10, the U.S. State Department called on Damascus to drop all remaining charges.

(Reporting by Mariam Karouny; Editing by Mark Trevelyan) ((mariam.karouny@thomsonreuters.com; +961 1 983 885; Reuters Messaging: mariam.karouny.reuters.net@reuters.com))

Keywords: SYRIA CRISIS/CAMPAIGNER