TURBAT, Pakistan - The smugglers moved their caravan at sunset through the desolate moonscape of western Pakistan, the backs of a dozen camels piled high with nearly a ton of heroin and morphine originating in Afghanistan.

Lying in ambush, soldiers from Pakistan's Anti-Narcotics Force shouted orders to halt. The smugglers responded with gunfire.

When the shootout a week ago was over, two smugglers lay wounded, one mortally; six were captured and a few escaped.

The haul - 1,430 pounds of heroin and 550 pounds of morphine with an estimated value of $550 million if it had reached the streets of Europe or America - is believed by U.N. drug officials to be one of the biggest ever.

The U.S.-led war on the Taliban had disrupted the world's biggest heroin trafficking route, from Afghanistan through Pakistan and onward to Europe. The flow of Afghan heroin - already pinched by an edict from Taliban leader Mullah Mohammed Omar banning opium poppy cultivation - dried to a trickle.

But now, with the Taliban defeated and the international community pressuring Afghanistan's new government to launch a comprehensive crackdown on drugs, traffickers have been moving huge amounts of heroin out of Afghanistan in the past two weeks, officials say.

"After several months of calm on the drug front, traffickers have decided to move their stocks out of Afghanistan," Bernard Frahi, the senior U.N. anti-narcotics official in Pakistan and Afghanistan, told reporters Saturday.

"They know that their stockpiles are going to be destroyed along with terrorist hiding places," Frahi said.

Although Omar ordered a halt to cultivation 18 months ago, the United Nations believes opium stocks remained from previous harvests, and some were likely grown illegally. Also, U.S. officials said last March that it appeared the anti-Taliban northern alliance had done nothing to stop cultivation or trafficking in the areas it controlled at the time.

Western dignitaries visiting Afghanistan over the past week, including British Prime Minister Tony Blair and nine U.S. senators, told Prime Minister Hamid Karzai's interim administration that one outcome of the U.S.-led war must be an end to his country's role in the heroin trade.

Afghans have increasingly relied on opium poppy cultivation since the war against Soviet occupation in the 1980s. For many farmers, growing opium is the only way of making a living in a shattered society where no other crops can be brought to market.

In 1985, Afghanistan produced 31 percent of the world's opium, according to the U.N. Office for Drug Control and Crime Prevention. By 1999, that had grown to 73 percent.

Warlords and tribal leaders paid their followers with opium money, and Pakistani and Russian traffickers grew rich getting the drug to market. About 90 percent of Afghanistan's heroin ended up in Europe.

In July 2000, Omar issued one of the most internationally friendly edicts of his rule, banning the cultivation of opium as being against Islam. Opium production fell 94 percent last year to 185 tons, the United Nations estimates.

But Omar never cracked down on trafficking. The Taliban earned revenue from levies on shipments. Opium and heroin still moved from Afghanistan southward into Pakistan, then took sea routes or went overland through Iran and Turkey into Europe. Other Afghan opium moved north into Tajikistan and Uzbekistan.

Since the Taliban collapsed, Omar's edict has been ignored by tribal leaders eager to get back into the business. New poppy fields have already been planted in Helmand and Kandahar provinces, the Taliban's southern heartland.

"We are expecting a bumper crop come April and May," said Maj. Gen. Zafar Abbas, director-general of Pakistan's Anti-Narcotics Force.

His forces have benefited from a three-year, $5 million U.N. program that provided them with pickups, motorcycles, night-vision gear and even camels and horses.

But he faces a clever enemy. The smugglers are turning away from road traffic to camels, plodding through remote ravines to avoid detection. They are also well-armed: a surface-to-air missile was recently seized.

The authorities showed off their drug haul from the Jan. 7 ambush Saturday at Turbat, a dusty outpost in sprawling, sun-scorched Baluchistan province near the border with Iran.

Confiscated pickup trucks, some riddled with bullets, also were on display, and the sad-looking survivors of the ambushed caravan were lined up. All were Iranians. They could face the death penalty.

"This is a game of hide and seek," Maj. Azhar Aref, who led the ambush, said of the smugglers. "They pay shopkeepers and drivers to tell them when we go out. We have to deceive them in order to catch them."

His men are paid less than $100 a month, and the major and general both acknowledged that a storeroom filled with seized heroin and hashish is a temptation to corruption.

"We have very little, but it happens," Aref said. "We start off by being very selective, taking only very moral people. But they are human beings, too."