A specially equipped U.S. ship has finished neutralizing all 600 metric tons of the most dangerous of Syria's chemical weapons components surrendered to the international community this year to avert threatened air strikes, the Pentagon said on Monday.

A Danish ship carrying some of Syria's most dangerous chemical agents began transferring them on Wednesday onto an American cargo vessel equipped with special gear to neutralise them at sea, officials said.

The U.S. Department of Defense has confirmed that the M/V Cape Ray (T-AKR 9679) was deployed from Portsmouth, Virginia on Monday for its mission to the Mediterranean Sea where it will be used to destroy Syrian chemical weapons at sea.