BAGHDAD, May 11: Guerillas attacked a 21-vehicle civilian supply convoy on its way to Baghdad from Jordan on Tuesday, a senior US military official said, and there were conflicting reports on whether some of the drivers were missing.

Several vehicles in the convoy were destroyed in the attack close to Rutba, near the Jordanian border, the military official told reporters. "A number of people are, as of a couple of hours ago, still unaccounted for," he said.

But Wendy Hall, a spokeswoman for Halliburton, said the convoy was run by a subcontractor of its unit, Kellogg Brown & Root, and that all drivers were accounted for.

"This was a second tier subcontractor to KBR and to our knowledge all drivers have been accounted for," she said. Last month, guerillas hit many civilian convoys, including one in which Mississippi truck driver Thomas Hamill was captured and held hostage for three weeks before he escaped from a remote shack on hearing the vehicles of a US patrol.

Coordinated attacks on convoys have diminished recently, although they are still the target of roadside bombs, a favourite weapon of guerillas. -Reuters