A helicopter has been shot down by a Taliban rocket propelled grenade attack in Helmand Province, Afghanisatan, resulting in the loss of four lives.

The four dead were American soldiers, according to Lt Col Joseph T Breasseale, a US military spokesman speaking to AP.

Meanwhile the Taliban, speaking to AFP, said that their fighters had brought the aircraft down in the Sangin district bazaar, using an RPG launcher.

The shooting makes it the sixth helicopter to crash in Afghanistan , either due to accident or enemy fire, since the invasion in 2001.

While RPG's are of limited use in bringing down aircraft on the move, they can be effective against helicopters when taking off and landing.

During the war against the Soviets in the 1980's Mujahhideen fighters abandoned RPG attacks on Russian helicopters after being equipped with US Stinger missiles, which unlike RPGs can lock onto their targets.

On Monday ten Nato soldiers were killed , while another was killed today in a roadside bomb, in addition to the four killed in the helicopter crash.