HERAT, Afghanistan (Reuters) - Air strikes in western Afghanistan this week destroyed a number of Taliban drug labs and also killed dozens of civilians, according to reports from local officials that were rejected by the Afghan government.

The Afghan defense ministry said coalition air strikes in three locations in the western province of Farah late on Sunday destroyed 68 Taliban drug labs and killed 150 insurgents, as part of an air campaign aimed at cutting off one of the movement’s key sources of revenues.

However Abdul Ghafoor Mujahid, the governor of Bakwa district, where the attacks took place, said many of those killed were civilians working in the labs. He said at least 45 civilians were killed in the strike, along with around 18 Taliban fighters. Several civilians in neighboring houses were wounded, he said.

“The civilians were hired by the Taliban to work in their heroin processing labs and were unfortunately killed during the air strikes,” Mujahid told Reuters.

Defense Ministry spokesman Qais Mangal denied any civilians were killed in the strikes in Farah, a remote and sparsely populated area where hundreds of police and soldiers have been killed in months of heavy fighting.

The attack followed a report from the United Nations last month which indicated that more civilians were killed by Afghan and U.S. air strikes in the first three months of the year than by any other means.

But it also underlined the ambiguity around how civilians working for the Taliban are classified.

U.S. forces were not immediately available to comment.

The Afghan government estimates that drug processing and taxation generate about $200 million annually for the Taliban and the campaign of air strikes over the past year has been aimed at cutting off a key source of revenue.

Despite peace talks between U.S. officials and Taliban gaining momentum, fighting has intensified in recent months as both the government and the Taliban announced their spring offensives but civilians still bear the brunt of the conflict.

As U.S. and Afghan forces have increased the number of air strikes, they have killed increasing numbers of civilians and in the first three months of the year they were the largest single cause of civilian deaths, killing 145 people, according to the latest UN civilian casualty report.