Antonio Maria Costa told the U.N. Security Council that since July his office and Interpol have been investigating numerous West African sites where they found large amounts of chemicals used to produce high grade cocaine and manufacture Ecstasy.

Costa, who directs the Vienna-based U.N. Office on Drugs and Crime, reminded the council that five years ago his office rang "the alarm bells" to warn the world about the destabilizing impact of cocaine trafficking from Latin America to Europe via West Africa, especially through Guinea Bissau.

In the past 18 months, Costa said, his office has noted "a significant drop" in drug seizures in West Africa and a similarly "strong decline in European drug seizures with West Africa as the suspected source."

"Since, generally, trends in seizures are a good proxy to determine what's happening to actual drug flows, we conclude that drug trafficking through the region has declined." he said.

Costa warned, however, that "this trend must be interpreted cautiously" because Europe's craving for cocaine persists and trafficking routes may have moved further south or inland.

He also cited three new "disturbing elements" which must be tackled.

Growing amounts of drugs coming into West Africa are being consumed locally which is new but not surprising, Costa said.

"Low prices and high supply of cocaine, particularly in Guinea-Bissau, cause havoc among a youth already so distraught by so many problems," he said.

Costa said there are also "reports of drug use (as well as trafficking) affecting the military."

"This threatens more than security sector reform," he said. "It creates armies of addicts."

Costa stressed that military forces around the world, in rich countries and poor ones, have experienced and addressed "the disastrous consequences of addiction" among their soldiers.

He said the new "shocking information" of drug production in West Africa is being processed.

"I want to ring a new set of alarm bells: West Africa is now on the verge of becoming a source of drugs, not only a transit area. Organized crime is growing indigenous roots," Costa warned, without naming specific countries.

The Security Council was meeting to discuss Secretary-General Ban Ki-moon's latest report on Guinea-Bissau where a rare, peaceful transition of power took place in July with the election of a new president, Malam Bacai Sanha. The tiny West African nation has been wracked by coups, countercoups and a civil war.

Costa said the sites where chemicals for drug processing were discovered were not in Guinea-Bissau, but just beyond its borders.

"Yet, something similar is likely to happen in Bissau where drug traffickers have acquired vast swathes of land and an important real estate presence," he warned. "The country is very vulnerable because of its poor judicial system, uncontrolled sea and air space and open land borders."