Cambodian authorities are already struggling to stem the flow of drugs

The Reuters news agency quoted an official as saying the 'Golden Triangle' of Burma, Thailand and Laos will now monopolise the Asian drugs trade.

The warning was delivered in the Cambodian capital, Phnom Penh, by Sandro Calvani, regional representative of the UN Drug Control and Crime Prevention office.

Borders closed

"The borders are completely closed in Afghanistan so you can't do any business, legal or illegal," Reuters quoted Calvani as saying.

"The Golden Triangle... is now moving all the drugs of Asia because Afghanistan is out of business for illicit drugs," he said.

Afghanistan's ruling Taleban were demanding Western recognition of the effectiveness of a ban last year on opium poppy cultivation, deemed to be contrary to Islam.

But vast stocks of the drug continued to pour across its borders until the latest crisis erupted following the suicide attacks two weeks in New York and Washington.

Market testing

Mr Calvani warned that drug traffickers had been "market testing" new smuggling routes through Cambodia to take advantage of the latest developments.

Authorities in the region have waged war for decades on the massive narcotics trade that flows across the Golden Triangle's porous borders.

Earlier this year, Thailand launched a military campaign aimed at closing down the trade along its border with Burma.

But Cambodia's underfunded law enforcement agencies and shaky legal system have struggled to keep up with the traffickers.