A local security official requesting anonymity Friday confirmed to VOA the casualty toll, saying the deadly strike occurred just outside the provincial capital of Lashkar Gah, where police forces were battling Taliban insurgents.
The Afghan security forces' casualties have risen recently as they struggle against a surge in attacks by Taliban militant group and other anti-government fighters.
Fourteen policemen were wounded in the attack, he added.
A USA military spokesman, Col. Dave Butler, said the air strike was called in by Afghan security forces who were taking heavy fire from Taliban fighters.
At least 11 other policemen were wounded in the clashes, the ministry said. Recently the Afghan forces backed by the US air power reclaimed a large territory from insurgents. "They [Afghan forces] reported and confirmed the areas were clear of friendly forces", said Butler. DW reports Zwak said that only eight police officers were killed in the North Atlantic Treaty Organisation strike.
"Unfortunately, they were not and a tragic accident resulted", the statement read.
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The rebels have targeted Riyadh with missiles and used drones to disrupt air traffic at Saudi airports near the Yemen border. Aramco also said in a statment that "oil and gas supplies to our clients have not been affected by terrorist attacks".
US officials are "examining the miscommunication to ensure it is not repeated", Butler said.
Further details about the incident are still forthcoming amid the absence of any official statement.
Meanwhile, the local Tolo News claimed that at least 17 policemen were killed in the incident. Afghanistan's beleaguered security forces come under near daily attacks by Taliban insurgents even as the United States is trying to broker a peace deal to end almost 18 years of war. Insurgents controlled slightly more than half of Helmand's territory, according to USA military data from October. Fighting has accelerated during a series of peace talks aimed at ending more than 17 years of war.
In a statement about the March air attack, the USA military said its forces had conducted "precision self-defense airstrikes on people firing on Afghan and American forces" who were conducting a ground operation near an Afghan army checkpoint. The white insurgent banners are often displayed along the roads from Lashkar Gah, sometimes in view of Afghan military bases.
The Taliban has so far rejected ceasefire proposals, saying USA and North Atlantic Treaty Organisation troops must first withdraw from Afghanistan.