Thousands of Syrian refugees stranded on Jordan's northeastern border with Syria are running out of food after a militant suicide attack prompted the army to shut the area, international relief workers and refugees said on Monday.

Jordan, a staunch U.S. ally, declared the area a closed military zone after a suicide bomber, believed to be an Islamic State militant, drove a vehicle last Tuesday from the Syrian side and rammed it into a military base close to Rukban camp, killing seven border guards.

Aid workers said convoys of food that normally go to the camp were being held up for a sixth day in Ruwaished, the closest town to Rukban camp, which is far from any inhabitable place. Only water trucks were being allowed through.