At least three Afghan policemen were killed and two wounded when a US military aircraft opened fire during an operation in southern Afghanistan, officials said on Saturday.
The so-called "friendly fire" incident occurred overnight, during a raid in Afghanistan's restive Helmand province, the US military command in Kabul said in a statement.
"We would like to express our deepest condolences to the families of the ABP (Afghan Border Police) members affected by this unfortunate incident," the statement said.
Omar Zwak, a spokesman for the Helmand governor, put the toll at three policemen killed and two wounded.
Both Afghan and American officials said they were investigating the incident.
Local police disguised as Taliban to ambush Taliban in Helmand.But Coalition believing they were Taliban hit them, killing a number of them.— sayed salahuddin (@sayedsalahuddin) June 10, 2017
Taliban fighters have made widespread gains in Helmand, seizing many of the province's districts and threatening the provincial capital of Lashkar Gah.
Hundreds of US Marines recently arrived in Helmand to take over an advising mission as part of the NATO-led coalition training and assisting Afghan forces.
American troops, including special forces, also carry out separate missions.
Air strikes and resultant collateral damage by American warplanes have greatly increased in recent months, as US President Donald Trump considers requests from military commanders for thousands more international troops.