UNITED NATIONS — The Afghan opium harvest is feeding a $65 billion global trade in heroin each year, which now kills many more people in NATO countries in a year than the number of NATO soldiers who have died on the battlefield in Afghanistan since 2001, Antonio Maria Costa, the senior United Nations official on drugs and crime, said Thursday.

“If we do not address this, it will be hard to solve all the other problems in Afghanistan,” Mr. Costa said, adding that the lucrative nature of the heroin trade is creating a “narco-cartel” in Afghanistan that includes corrupt government and security officials.

It is easier to try to uproot the heroin trade at its source, where opium is grown, than its destination, he said, particularly because heroin trafficking is disrupted less effectively in affluent Western countries, despite their financial and police resources.

Mr. Costa was summarizing a report from the office he heads, the United Nations Office on Drugs and Crime, which was released on Wednesday.

The opium crop from Afghanistan is refined to produce 375 tons of heroin, which makes up the bulk of the trade worldwide.

Drawing on figures supplied by the countries themselves, the United Nations report says that Iran intercepts 20 percent of the 105 tons of heroin that flows through its territory, Pakistan 17 percent of the 150 tons that comes in and Central Asian countries only 5 percent of the 100 tons that enters these nations.

Europeans consume about 88 tons of heroin per year, and the authorities seize only 2 percent of the heroin that enters Europe, mostly through Bulgaria, Greece and Romania, according to the report.

The annual death toll in all NATO countries from heroin overdoses is estimated to be more than 10,000, an annual total that is about five times higher the number of NATO soldiers killed in Afghanistan in the past eight years, the report said.

The proceeds from the heroin trade help fuel the Taliban insurgency. When the Taliban were in power a decade ago in Afghanistan, heroin produced $100 million a year in taxes, the report said. The insurgents are now estimated to be gaining $160 million a year from trafficking in the drug.

Mr. Costa recommended that NATO forces concentrate on trying to dismantle the drug cartels in Afghanistan, instead of striking at individual farmers and crops.

By bombing drug laboratories, along with attacking traffickers and open drug markets, NATO troops have had limited success, he said, but they need to extend their reach.