Gen Martin Dempsey, chairman of the US Joint Chiefs of Staff

An insurgent rocket attack on a US air base in Afghanistan has damaged the plane of America's top military officer while he was on a visit there.

Gen Martin Dempsey, chairman of the US Joint Chiefs of Staff, was not near the plane at the time but two US maintenance crew were slightly injured, reports the BBC.

The attack happened late on Monday night at the US air base in Bagram.

He was in Afghanistan to discuss a growing number of attacks against Nato soldiers by Afghan security personnel.

Gen Dempsey had arrived on Monday in a C-17 transport aircraft which was parked at Bagram. A NATO spokesman said that the general had left Afghanistan by Tuesday morning using another plane.

"He was nowhere near the aircraft. We think it was a lucky shot," NATO spokesman, Col Thomas Collins is quoted as saying by Reuters news agency.

There have been insurgent attacks against the heavily fortified base, located about 30 miles (50km) north of Kabul.

In May 2010 militants launched a co-ordinated assault on Bagram, injuring several NATO troops. Two US soldiers were killed in a similar attack in June 2009.