BASRA, Iraq: Kuwait and Iraq separately denied an attack took place against a convoy carrying equipment for American forces.

An explosion near the Jraischan border crossing between Iraq and Kuwaiti on Monday evening targeted a convoy carrying equipment for US forces, three Iraqi security forces told Reuters.

It was not immediately clear if there were any US troops in the convoy or if anyone had been injured in the explosion, which went off just before 9 p.m. Baghdad time.

The US military said Tuesday it was investigating a militant claim by a newly formed Iraqi Shiite militant group of a bombing at the Iraq-Kuwait border.

A little-known Iraqi Shiite militia group by the name of Ashab Al-Kahf claimed responsibility for the attack and published a video showing an explosion at a distance. It said it was able to destroy US military equipment and large parts of the crossing.

Kuwait’s Armed Forces on Twitter denied the attack on one of the outposts on its northern border with Iraq, affirming that boarders are stable and secure.

Vehicles are regularly loaded with military equipment at the crossing, the sources said, and the cargo is usually loaded or unloaded before entering or exiting Iraq.

Foreign companies are contracted by US forces to provide security in the area, the Iraqi security sources said.

A security source had earlier said that the explosion was caused by an Iraqi Shiite Muslim militia targeting a US military base near the crossing by smuggling in an explosive device, and that some staff on the base had been injured. This was later contradicted by other security sources who said a convoy was attacked, not a base.

The Iraqi Shiite militant group, called Ashab al-Kahf, issued a statement overnight claiming it destroyed “equipment and vehicles belonging to the American enemy” in a bombing targeting a border crossing south of the Iraqi city of Basra.

The group later published an 11-second video clip it claimed showed the blast, according to the SITE Intelligence Group, which monitors militant groups.

The out-of-focus video shows what appeared to be an explosion and lights in the distance, with a man speaking in Arabic. The Associated Press could not immediately verify the video.

US Army Maj. John Rigsbee, a Central Command spokesman, said the American military was looking into reports of the explosion.