International and Afghan forces have killed 60 militants and seized 102 tons of opium poppy seeds, drugs and chemicals during a four-day operation in southern Afghanistan, the U.S. military said Saturday.

It was one of the biggest drug seizures by foreign troops in Afghanistan since their arrival in 2001, the military said.

The attack "severely disrupted one of the key militant and criminal operations and narcotics hubs in southern Afghanistan," the military said in a statement.

The forces seized 83 tons of poppy seeds, along with tar opium, processed morphine, processed heroin and hashish, it said. They also captured hundreds of gallons of chemicals used to process heroin.

The military said it was its final tally of deaths and seizures in the fighting that started May 19 in the city of Marjah in Helmand province. U.S. forces issued a number of updates during the fighting, raising the militant death toll and the amount of drugs and materials captured. The Defense Ministry also backed the figures, along with a provincial spokesman, Dawood Ahmadi.

Western officials have warned for years that booming drug production in southern Afghanistan, where the insurgency is strongest and the government weakest, is funding the Taliban's war.

Meanwhile, Britain's Defense Ministry said one of its service members was fatally shot while on patrol in another part of Helmand on Friday, while another NATO service member died in Uruzgan province when a helicopter made an emergency landing. The crash was not caused by insurgents, the international coalition said, but gave no further details.

And in Ghazni province a group of Taliban fighters ambushed police in a market early Saturday and one civilian was killed in the firefight, deputy provincial police Chief Abdul Ghazni said.

The Taliban have taken back control of large areas of southern Afghanistan in the past three years, reversing much of the gains won by international forces in the 2001 offensive that toppled the hard-line regime from power.

About 21,000 additional U.S. troops are arriving in Afghanistan — mainly in the south — as part of President Obama's plan to turn back the resurgent militants.