Blasts hit US-backed anti-IS force's arms depot in Syria

"At least five explosions occurred on Saturday morning at the arms and munitions depots in a base close to Tal Tamer" northwest of the city of Hasakeh, the head of the Syrian Observatory for Human Rights, Rami Abdel Rahman, told AFP. 

He said the base was used by Kurdish forces from the People's Protection Units (YPG) as well as members of the international coalition fighting IS in Syria and neighbouring Iraq.

Contacted by AFP, the coalition said there had been "no reports of explosions" at the site. 

A local Kurdish official said a number of people were wounded in the blasts and loaded on to ambulances. 

Neither the observatory nor the official could specify the cause of the explosions. 

It was not clear if there were any US personnel on the base at the time of the blasts. 

A witness told AFP that "successive explosions occurred between 10:30am and 11am (8:30am to 9am GMT)" and said ambulances and firefighters arrived swiftly at the scene. 

On Thursday, the US announced the death of an American serviceman in Syria, who was killed by an improvised explosive device. 

For more than two years the US has led a 66-nation coalition that has been waging air strikes against IS positions in Syria and Iraq.

Washington has also deployed special forces in Syria to advise the Arab-Kurdish alliance, the Syrian Democratic Forces, and improve the coalition's targeting of air strikes.

As many as 300 US special forces personnel may be in Syria.