KABUL: An Afghan air force strike killed five soldiers and a police officer in western Afghanistan, an official said on Saturday, the latest in a series of so-called “friendly fire” incidents.

Afghan helicopters “mistakenly” bombed their own forces after calling in air support as they battled the Taliban in the Kensk area of Farah province late on Friday, Dawlat Waziri, a defense ministry spokesman, said.

“Because of the wrong coordinates, helicopters bombed an Afghan forces’ checkpoint that unfortunately left five soldiers and one police officers dead,” he said. “An investigation into the incident has been launched,” he added.

Last month a US air raid killed eight Afghan policemen in the southern province of Uruzgan, in the first such incident since American forces were given greater powers to strike at insurgents.

The US military in Afghanistan, however, said its forces were not involved in the air strike in Farah.

Civilian and military casualties caused by Nato and Afghan forces have been one of the most contentious issues in the 15-year campaign against Taliban insurgents, prompting harsh public and government criticism.

A US air strike killed up to 10 Afghan soldiers in July last year at an army checkpoint in Logar province south of Kabul, one of the deadliest episodes of “friendly fire” by foreign forces in recent years.

Afghanistan has a tiny air force compared to Nato’s fleet, which carried out supply operations, air strikes and emergency evacuations until the drawdown of foreign coalition forces in 2014.

The air force has recently began bombing Taliban militants as the fighting rages in several provinces across the country. Meanwhile, Taliban fighters have advanced closer to Lashkar Gah, capital of the strategic southern province of Helmand, pushing into a farming district on the other side of the river from the town, officials said on Saturday.

Though the Western-backed government in Kabul pushed the insurgents back with the aid of US air strikes in August, it is struggling to reverse the tide of the fighting.

Capturing the city would give the Taliban their first provincial capital since the northern city of Kunduz fell briefly a year ago and would reinforce the impression that government forces are losing momentum in the war.

The insurgents, who control large sections of the opium-growing province, are now in Bolan, an agricultural zone that links Lashkar Gah with Gereshk, a town that straddles the main Highway One, as well as Marjah district centre to the west. “The Taliban came to our villages, blocked the main road and are attacking security forces,” said local resident Rozi Mohammad.

Local officials said security forces were engaging the insurgents and were expected to begin offensive operations soon though they faced strong opposition.

“We are about 300 metres away from the Taliban positions. They are firing at us from residents’ homes and we are waiting for fresh forces to repel them,” said Hesmatullah, a policeman whose unit was involved in the fighting.

Published in Dawn, October 2nd, 2016