U.S.-led coalition forces killed 76 Afghan civilians, mostly women and children, in a Friday attack in western Afghanistan, said the country's Interior Ministry.

"Seventy-six civilians, most of them women and children, were martyred today in a coalition forces operation in Herat province," the Interior Ministry said in a statement.

Nineteen women, seven men and the rest children, all under 15 years of age, were killed, the statement said.

The civilians were killed when coalition forces bombarded the Shindand district in Herat Friday afternoon, the ministry claimed.

Coalition troops denied killing any civilians in the air strike.

Coalition forces confirmed they killed 30 militants in an air strike early Friday morning in the Shindand district, but denied initiating any air strikes later in the day.

"We stand by our account and our reports and what we know and I can't reconcile why [the Interior Ministry] would have a different figure," U.S. military spokeswoman Lt. Col. Rumi Nielson-Green said Friday.

The Friday morning air strikes were in response to militant ambushes of coalition troops in Herat, the U.S. military said in a statement.

The overnight attacks by U.S. forces claimed the lives of civilians, a local council member in Herat told Reuters news agency.

Reports of civilian deaths in the attack differ widely. The U.S. Defence Ministry in Kabul said five civilians perished in the attack, while a senior police officer told Reuters that "more than 30," civilians lost their lives.

The issue of civilian casualties in air strikes in the conflict in Afghanistan has been a sensitive one. NATO has admitted its air strikes have caused many civilian deaths.

Afghan President Hamid Karzai has repeatedly condemned civilian deaths and earlier this month said air strikes succeeded only in killing civilians, not subduing insurgents.

More than 3,400 people — mostly militants — have been killed in insurgency-related violence this year, according to figures from Western and Afghan officials.