NATO-led troops backed by artillery and airstrikes battled insurgents in southern Afghanistan, killing 48 suspected militants in three separate confrontations, the alliance said Wednesday, as Afghan police and Western troops elsewhere seized more than 10 tons of marijuana from a truck.

At least four civilians also were wounded in the clashes in Kandahar's Zhari and Panjwayi districts on Tuesday, the alliance said, adding that they were receiving treatment at military medical facilities.

The clashes had targeted militants who were attacking NATO's development efforts in the area, said Maj. Luke Knittig, a spokesman for NATO'sInternational Security Assistance Force.

NATO-led troops used mortar, artillery and air support in the rolling clashes with large groups of insurgents, a NATO statement said.

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The troops "positively identified insurgents, killing an estimated 48," NATO said. "We deeply regret any civilian casualties caused."

NATO forces launched a major military operation in the Panjwayi area in September. The alliance said it killed more than 500 suspected militants during that offensive.

NATO-led troops and Afghan police, meanwhile, seized over 10.3 tons of marijuana from a truck in southern Afghanistan, the alliance said Wednesday.

The truck was stopped near Qalat in Zabul province on a road that links the southern city of Kandahar to Kabul, an alliance statement said without providing the exact day when the seizure was made. Four people in the truck were detained.

Marijuana is illegal in Afghanistan but officials here concentrate more on the fight against the opium trade.

In the country's west, U.S. and Afghan troops recovered over 55 kilograms of opium from a car in Farah province, another NATO statement said Tuesday.

The U.S. soldiers were supporting an Afghan National Army checkpoint when a car failed to stop, the statement said. An Afghan soldier noticed a suspicious bag where the spare tire was supposed to be and alerted the next checkpoint. A search of the vehicle there netted 55 kilograms of opium. The car's driver and passenger were detained.

Afghanistan's world-leading opium cultivation rose 59 percent this year, according to U.N. figures released last month.

The record crop yielded 6,100 tons of opium, or enough to make 610 tons of heroin — outstripping the demand of the world's heroin users by a third, according to U.N. figures.

According to the U.N.'s Office on Drugs and Crime, some 2.9 million people were involved in growing opium, representing 12.5 percent of the total Afghan population, and that revenue from this year's harvest was predicted to hit over US$3 billion (euro2.4 billion).

Opium cultivation has surged since the ouster of the Taliban in late 2001. The former regime had enforced an effective ban on poppy growing by threatening to jail farmers — virtually eradicating the crop in 2000.

But Afghan and Western counter-narcotics officials say Taliban-led militants are now implicated in the drug trade, encouraging poppy cultivation and using the proceeds to help fund their insurgency.

The U.N. anti-drug chief also urged the government to crack down on big traffickers and remove corrupt officials and police officers fueling the trade.

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