Colombian criminal gangs run the worldwide [cocaine] trade

Edward Venning NCIS

An estimated 30 tonnes of heroin and up to 40 tonnes of cocaine entered the country last year.

The UK market for cocaine is also growing, and is now thought to be worth in the region of �2-�3bn annually at street level.

Colombia is the world's dominant producer of cocaine, according to the National Criminal Intelligence Service (NCIS).

NCIS's Edward Venning told BBC News Online: "Colombian criminal gangs run the worldwide trade. Most is exported to the US but substantial amounts are targeted at Europe.

'Mother ships'

The finished cocaine is moved from laboratories by light aircraft to the Caribbean and coastal areas.

Small boats are often used to transfer drug shipments

Drugs are then usually transferred at sea to "mother ships", bulk cargo carriers destined for European ports which usually carry legitimate loads as well.

They then carry bulk loads across the Atlantic from major South American ports, with the cocaine concealed as part of the cargo or in containers, said Mr Venning.

Some head directly to European ports such as Rotterdam, Antwerp and Hamburg, from where the drugs are distributed throughout Europe.

Distribution

But frequently the cocaine has already been "coopered" - off-loaded at sea to smaller vessels, usually off the coast of Spain or Portugal.

Most of the world cocaine supply comes from Colombia

"Galicia in northern Spain is a popular spot," Mr Venning said.

"It has a similar profile to Cornwall, quite remote with a low population density and a tradition of smuggling."

Once in Spain, the drug consignments are broken down into smaller quantities and distributed.

"Spaniards take over the distribution into Europe by haulage, in return for a proportion of the cocaine. Then it gets into the supply chain and filters through to dealer level."

Heroin

Getting it from there to the UK is more difficult, but smugglers use every available route from small ships and planes to packages sent through the mail.

A recent trend has been the use of couriers coming in via the Caribbean and especially Jamaica, to British airports, the NCIS's spokesman added.

Most heroin is grown in Afghanistan and arrives on British shores via western Iran or organised criminal gangs in Turkey.

Turkish crime groups are believed to be responsible for 90% of all heroin found in the UK, said Mr Venning.

Although the Taleban regime in Afghanistan has banned the growing of opium - from which heroin is derived - Mr Venning said the supply was likely to remain unaffected for some time as Afghani-produced heroin takes 12-18 months to arrive on British shores.

But unconfirmed reports have suggested that some UK dealers are taking advantage of the current situation to off-load some of their poor quality stock, he said.

Although the price of heroin on the Pakistani border has halved from $400 to $200 per kilo since the 11 September terror attacks on the US, Mr Venning said this was unlikely to bother the major heroin traffickers.

"The Turkish organised criminal gangs are the ones that make all the profit," he said. "They get �13,000 per kilo selling in the UK."