LASHKAR GAH, Afghanistan (Reuters) - A U.S. air strike killed as many as eight Afghan policemen outside the embattled provincial capital of Uruzgan province, Afghan officials said on Monday, as security forces, supported by U.S. strikes, battle resurgent Taliban militants.

An initial air strike late on Sunday killed one policeman, while a follow up strike targeted first responders, killing at least seven, said Rahimullah Khan, commander of the reserve police unit in Uruzgan.

Another official, Uruzgan deputy police chief Mohammed Qawi Omari, put the death toll at six but also reported the police were killed by a foreign air strike.

The U.S. military command in Kabul confirmed its warplanes had conducted an air strike in the area, but said they targeted “individuals firing on, and posing a threat to” Afghan national security forces.

“We don’t have any further information on who those individuals might have been or why they were attacking ANDSF (Afghan national defense and security forces),” U.S. military spokesman Brigadier General Charles Cleveland said in a statement.

“U.S., coalition, and Afghan forces have the right to self-defense and in this case were responding to an immediate threat.”

Afghan officials said they were investigating the attack and were in contact with the U.S.-led coalition.

Afghan security forces, supported by American air strikes and international military advisers, are battling Taliban militants who have fought a 15-year insurgency against the Western-backed government in Kabul.

Taliban fighters briefly entered Uruzgan’s capital city, Tarin Kot, in early September, according to provincial officials, before being pushed back by security forces.