Ali Hashemi, head of Iran's anti-narcotics headquarters, told the Financial Times that estimates of this year's opium harvest in Afghanistan ranged from 3,500 to 4,000 tonnes, close to the record crop of 4,600 tonnes in 1999.

Afghanistan's poppy fields provide 90 per cent of the heroin that reaches Europe, mostly transiting Iran.

A ban on opium poppy cultivation imposed by the Taliban in its last year in power resulted in one of the lowest crops in recent years - less than 200 tonnes in 2001.

But Mr Hashemi said crop substitution programmes had not been implemented and western governments had shown a "lack of co-operation" in dealing with drugs.

Describing Afghanistan as a "nexus of drugs, crime and terrorism", an official of the United Nations Office of Drugs and Crime said the power vacuum that followed the overthrow of the Taliban a year ago allowed farmers to plant poppies again.

A UN survey showed that five Afghan provinces were heavily economically dependant on cultivating opium, he said. But another UN official pointed out that a growing amount of opium was originating in areas under the control of the Northern Alliance, which acted as US ground forces and now dominates much of the central government in Kabul.

Mehdi Abui, a senior anti-narcotics police commander in Iran, said clashes between Iranian security forces and heavily armed drug smugglers had increased this year, especially on the border with Pakistan.

Officials noted that although the Taliban had been heavily involved in the international drugs trade, their removal from power had not affected the ability of the armies of smugglers operating in Afghanistan and Pakistan.

Iran News on Monday expressed a commonly held sentiment in Iran that hundreds of Iranian police and soldiers are losing their lives fighting the smugglers in order to save Europes youth from the scourge of heroin.

"The Iranian public is sick and tired of spending tax payers money and sacrificing the precious lives of its younger generation in a struggle whose prime beneficiary is the western world," the newspaper commented.

But it is only in recent years, in an atmosphere of more open debate fostered by President Mohammad Khatami, that Iran has started to face up to its own drugs epidemic with addicts estimated to number more than 2m.