According to the World Bank, Afghanistan produces 90 per cent of the world's illegal opium.

The Taliban in Afghanistan made more than $100 million in 2007 from imposing taxes and providing protection to the country’s huge opium trade, the United Nations anti-narcotics chief said Tuesday.

Speaking to BBC radio, Antonio Maria Costa of the United Nations Office on Drugs and Crime [UNODC] said Afghan insurgents collected a 10 per cent tax on the earnings of opium poppy farmers and processors in Taliban-controlled areas.

There were also other ways that the group skimmed money from the more than $1 billion generated last year by Afghanistan's opium trade, Costa said.

"One is protection to laboratories and the other is that the insurgents offer protection to cargo, moving opium across the border," he said.

Since the Taliban were forced from power in Kabul by a U.S.-led invasion in 2001, Afghanistan has become the world’s leading producer of opium.

By some estimates, more than 90 per cent of the world’s heroin originates in the opium poppy fields that can be found in almost all 34 Afghan provinces.

U.S. troops ignore poppies in south

In the last years of Taliban rule in the country, the extremist militia had all but wiped out opium production, calling it un-Islamic and punishing drug dealers. But poppy farming has surged since then and Afghan militants are using money from the drugs trade to fight NATO troops in the country, officials say.

Anti-narcotics efforts in post-Taliban Afghanistan have failed to stem the narcotics trade with farmers and processors last year producing a record 8,000 tonnes of opium.

U.S. troops in the south of the country are now instructed not to interfere with poppy crops, according to a report this week by the Associated Press from Helmand province, one of the prime sources of Afghan opium.

"Poppy fields in Afghanistan are [like] the cornfields of Ohio," U.S. Marine Staff Sgt. Jerry Stover told an AP reporter embedded with his platoon in Helmand. "When we got here, they were asking us if it’s OK to grow poppy, and we said, ‘Yeah, just don’t use an AK-47 [assault rifle].’"

Production is expected to be lower in 2008, the UN’s Costa told the BBC, because of drought and a glut on world markets from record harvests in earlier years.

"Last year, Afghanistan produced about 8,000 tonnes of opium," he said, "The world in the past few years has consumed about 4,000 tonnes... This leaves a surplus. It is stored somewhere and not with the farmers."

It is not known whether these stockpiles are held by traffickers, corrupt Afghan officials and politicians, or the Taliban themselves, but they represent hundreds of millions of dollars, Costa said, raising fears that even more money could be spent on fighting NATO and Afghan troops.

Canada has 2,500 soldiers in Afghanistan, most in the southern province of Kandahar, which ranks near the top of opium producing areas of the country.