The Thai army is trying to crack down

The title had been held for the last three years by Afghanistan, but recent events there have cut production from 4,000 tonnes per annum to just a few hundred.

Golden triangle drug lords want to plug that gap - especially in the western European markets, where Afghanistan supplied up to 90% of the heroin used on UK streets.

I am travelling with a unit of the Thai Armed Forces as it patrols a section of the Golden Triangle looking for opium poppy fields, the crop that produces heroin.

Against a clear blue sky a Thai military helicopter soars high above a stretch of jungle as beautiful as it is notorious.

'New plants'

Behind me sits a Thai Air Force gunner keeping a beady eye on the hills below. The drug lords who operate in the region have the capability to shoot our helicopter down.

New techniques are being used to grow more poppies

Lieutenant-General Udomchai Onga-kasing

It is not long before we find what we have been looking for - clearings in the dense jungle, little fields pock-marking the ground. Opium poppy fields.

On the ground we get a closer look. A lieutenant-general in the Thai Third Army leads me to a field about the size of two tennis courts. In front of us are neat little rows of white flowers - young opium buds, fluttering in the light breeze.

To one side a garden sprinkler feeds water to the buds. A new development here in the cultivation of opium poppies, says Lieutenant-General Udomchai Onga-kasing of the Thai Army.

He says the sprinklers are evidence that drug lords are now ordering local farmers to grow more opium poppies, in order to dominate the global heroin market.

"New techniques are being used to grow more poppies," he says. "Farmers now use fertilisers and pesticides.

"And they're now irrigating the land using sprinklers so the planting season is much longer."

Chasing the dragon

All around me now in this field, soldiers with Ak-47s slung over their shoulders are hacking away at the opium poppies, flattening the drop using long rubber whips. But the destruction of this field is a tiny victory in the war against drugs here.

The Golden Triangle covers a vast area - impossible to monitor completely.

In a jungle clearing in northern Thailand, a young woman chases the dragon. I watch as she uses a straw to inhale the noxious fumes of a tiny amount of heroin heated on a spoon by a candle.

The woman, who refused to tell me her name, is typical of so many in the remote reaches of the Golden Triangle. They have grown up with drugs. Opium has been used for centuries in these parts, for medicinal purposes as well as to get high.

But some villages are turning their backs on drugs, at the behest of the Thai Government.

A village elder in northern Thailand, Toop Pia Kom, says his community gave up smoking opium to years ago. He says it was ruining too many people's lives - that it had to stop.

UN fears

But there are still many people in the Golden Triangle who are addicted to drugs, and there are many poor farmers willing to plant their fields with opium poppies rather than with less lucrative Thai fruits for example.

Opium is the crop that produces heroin

It is a big worry for the international community, following Afghanistan's demise as a drug producer.

"There is certainly a risk that South East Asia will play a more important role in the supply of heroin to western Europe and the UK," says the regional representative of the United Nations International Drug Control Programme in Thailand, Yngve Danling.

"We are very worried about this and we are working with governments in the region to improve co-operation and improve facilities for fighting drug production."

As Thai soldiers finish off destroying a field of opium poppies, the Thai Government is renewing its appeal for help from the international community in the war on drugs: for money and better surveillance equipment to help win the battle.

Opium and heroin have ruined ruined many lives. Afghanistan used to be a major culprit - now it is the drug lords of lands of the Golden Triangle who want to increase their profits from the misery of others.