The alleged attack comes days after the Taliban targeted a US convoy in north-eastern Afghanistan, killing three soldiers

Taliban militants have claimed they shot down a US B-52 heavy bomber, Syrian news site Muraselon reports.

The incident purportedly took place when the aircraft was departing from the Shawrab Airbase in southern Afghanistan in the early hours of Wednesday morning.

"Mujaheddin (a militia fighter) of the Islamic Emirate targeted a US B-52 bomber with heavy weapons today early morning in Lar area in the Washir district of Helmand Province," a spokesman for the Taliban was quoted as saying.

The B-52 is said to have crashed after the strike, killing all of its crew. Both Afghan and US authorities are yet to comment on the matter.

On 8 April, three US service members were killed in a car bomb attack on a convoy near the Bagram Air Force Base in north-eastern Afghanistan. The terror group claimed responsibility for the bombing.

The Taliban emerged in 1994 at the height of a civil war in Afghanistan. The group held power in most of the country between 1996 and 2001; during this period, it introduced Islamic Sharia law.

The Taliban was ousted from power by a US-led coalition in 2001 and has since then been waging a guerrilla war against the Kabul-based government, and NATO forces in Afghanistan and neighbouring Pakistan.

Russia's envoy to Afghanistan said in February that the militants control at least 50 per cent of Afghanistan's territory and their ranks include from 3,500 to 10,000 Daesh fighters, who regularly carry out terror attacks across the country.