The aeroplane returned safely to base after the incident in the early hours of Wednesday.

"Our plane was shot at ... but there was no damage," a US diplomatic source told the AFP news agency.

"The [Tuareg] rebels did it," the source said.

Major John Dorrian of the US command in Stuttgart, Germany said, however, that there had been slight damage to the C-130 aircraft.
  
He said that the damage was most likely caused by "small arms fire, probably rifles".

The attack followed a joint exercise involving US troops and the armies of several Sahel states, the vast region bordering the Sahara desert, aimed at countering the threat of terrorism in the region, officials, who asked not to be named, told the Reuters news agency.

Attacks and ambushes

Mali's armed forces have been searching for Tuareg rebels in the desolate northern mountain region of Tinzaouatene on the borders with Algeria and Niger after several attacks and ambushes in recent weeks.

Earlier this month Mali appealed for international help to counter raids by the Tuaregs, who they also accuse of trafficking drugs and weapons.

Washington has been helping the hunt for armed fighters in the region and expanded a series of programmes for training African militaries.

The Bush administration has also approved the Trans-Saharan Counter Terrorism Initiative (TSCTI), which has economic, social and political components designed to complement military activities.

Nomadic Tuaregs in northern Niger and Mali staged an uprising in the former French colonies in the 1990s.

Tuaregs have long complained of being neglected and marginalised by governments ruling far away in the south.