The US ambassador to Damascus has said a newly formed militant alliance in Syria has refused to meet with American officials, in an interview aired Wednesday on Al-Arabiya television.

The US ambassador to Damascus has said a newly formed militant alliance in Syria has refused to meet with American officials, in an interview aired Wednesday on Al-Arabiya television.

"The Islamic Front has refused to sit with us without giving any reason," Robert Ford said, a day after US State Secretary John Kerry described as "possible" a meeting with Syria's biggest militant alliance.

"We are ready to sit with them because we talk to all parties and political groups in Syria," Ford was quoted as saying on the Dubai-based channel's Arabic website.

Last week, the Front overran the northern headquarters and two warehouses belonging to the US-backed Free Syrian Army, prompting Washington to cut off non-lethal aid to the main secular militant group in the north.

In Washington, State Department deputy spokeswoman Marie Harf said earlier that if a meeting with the Front did take place, the United States would expect the return of its stolen non-lethal assistance.

Washington has said it is already meeting with a broad section of Syrian groups to try to end the nearly three-year war through negotiations, but has explicitly ruled out any contacts with those linked to Al-Qaeda or designated as terrorists by the US.