Taliban fighters seized a district headquarters in Afghanistan’s Helmand province on Monday despite repeated US air strikes to repel them, adding to the insurgents’ recent advances in an opium farming region near a hydroelectric dam.

Elsewhere in Helmand, two men in military uniforms opened fire in the former British base of Camp Bastion yesterday, killing two US service personnel, before being shot dead themselves.

It was the second incident this year involving Afghan troops, or people wearing Afghan uniforms, shooting at foreign soldiers.

Pentagon spokesman Captain Jeff Davis said the attackers were wearing Afghan uniforms and opened fire on the vehicle in which the Americans were travelling. An Afghan regional official said the incident involved Afghan special forces firing on allies at the former Camp Bastion, which was handed over to Afghan forces last year.

Helmand’s Musa Qala district fell after the Taliban overran police and army posts to retake a district that was wrenched from them by British and Afghan troops eight years ago. US warplanes have bombarded Musa Qala since the weekend, killing up to 40 militants, with two air strikes on Tuesday. But they regrouped, chasing the district government out of town and seizing weapons.

“Afghan special forces, police and commandos have been deployed to Helmand in order to retake Musa Qala district. Foreign air strikes are backing our forces,” said Dawlat Waziri, a spokesman for the defence ministry. In Afghanistan’s first summer fighting season since foreign troops stepped back from combat roles, the Taliban have pushed into several districts in the North and South but have mostly struggled to keep hold of them. Last week, Afghan forces pulled out of the town of Nawzad, the headquarters of a neighbouring district that was also fiercely fought over when British and US forces were stationed in Helmand, the country’s main opium production centre.

That means the Taliban currently control three districts in northern Helmand and have partial control of several others, including Kajaki, where they frequently disrupt supplies from a large US-built hydroelectric dam powering the province.

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