The U.N. International Narcotics Control Board said overall drug usage appeared stable, but soaring opium production in Afghanistan was fuelling heroin use in its neighbours and globally.

It also warned that drug smugglers were increasingly using West Africa as a transit point to bring cocaine and other substances into Europe from Latin America by air and sea.

The board said too many governments disproportionately targeted ordinary addicts and street dealers while doing too little to tackle the larger narcotics gangs -- and letting high-profile users walk free.

"The fact is that when a celebrity uses drugs, he or she breaks the law," board member and report author Hamid Ghodse told a news conference in London. "Young people are quick to pick up on, and react to, perceived leniency... It also makes people become cynical about drug enforcement."

He refused to name any particular individuals or countries considered too soft on famous users.

To be effective, authorities must get tougher on those at the top of the illicit drug trade, Ghodse said, adding that because this was not easy, many law enforcers chased the easy pickings at the bottom of the pyramid.

Overall, Ghodse said, more coordination across borders was key to cracking the trade. But he said the situation in the world's fastest growing drug producer Afghanistan, now producing more than 93 percent of global opiates, was out of control.

Despite attempts to curb poppy growing, opium production has grown steadily from a low point in 2001, shortly before the Islamist Taliban were ousted by U.S.-led forces.

The report attributed the world's highest addiction rate -- almost 3 percent of adults in Iran -- on Afghan heroin.

INCB said part of the problem was that key chemicals used in refining opium into heroin were being freely allowed into Afghanistan. Drug control has become secondary as U.S., NATO and Afghan forces try to stop a resurgent Taliban in the southern drug producing provinces.

"The answer has obviously to begin with security, tackling the insurgency," Ghodse said. "But we should also be tackling eradication and not waiting until we have dealt with one to deal with the other... Despite all the efforts that have been done we have lost control, but that does not mean it is impossible."

Opiates such as morphine can serve a medical purpose as painkillers -- but Ghodse said legal demand for medical opiates would not come close to soaking up Afghanistan's current 8,200 tonne crop.