Paul Rocks BBC News Online - Costa del Sol

It is a trade thought to be more lucrative than drug smuggling but without the risk and social stigma.

Tobacco smuggling is big business with plenty of smokers willing to buy the goods at a cut price.

It is also an illicit trade, I suspected, being dominated by organised criminal gangs, but here on the Costa del Sol I was amazed to hear of the extent it involved people outside the recognised criminal fraternity.

THE PROFIT MARGIN

200 packet in Spain �17 200 packet in UK �45 Smugglers sell for �27 Profit margin = �10

Click for more on customs limits

A flight out of Belfast is bustling with people looking forward to a little bit of winter sun.

But for some on the flight, they will not even see the sunrise. They are set to return on the same plane in several hours' time.

It is a journey well rehearsed because this trail has become more popular as word of mouth spreads the news of money being made.

A tobacco wholesaler in southern Spain, who did not want to be identified, told me how the smugglers were operating.

"These guys are getting off a plane at Malaga and making the short trip to see me in Torremolinos with their two empty suitcases each.

"They usually buy about 150 cartons, fill the cases and head straight back to the airport. They'll be on the same flight back that they came out on," he said.

"They are selling them on at about �27, making an average of �1,500 on every trip. With plenty of low cost airlines now flying into Malaga from all over the UK, these guys are doing alright for themselves."

Quick profit

More than one million cigarettes were found by customs at Belfast International Airport recently, in cases apparently abandoned when officers began making checks.

That would mean more than 30 people being involved if each was carrying about 150 cartons.

The focus has mainly been on ferry ports

The contraband, all with EU duty paid in Spain, was not thought to have been smuggled by a single gang, but by individuals tempted by a quick profit. And why?

A typical 200 carton of cigarettes costing �45 in the UK is being bought in Spain for 26 euro, or just under �17. They are being sold for about �27.

With that kind of margin, the smugglers are more than prepared to lose a couple of case loads to customs along the way.

While the seizure at Belfast International Airport will be seen as a success for customs officers, it is believed to be only the tip of the iceberg in terms of cigarettes being brought into the UK illegally.

The traditional focus had been on the cross-channel ferry ports but, unlike alcohol, cigarettes are transported and concealed much more easily.

And it is not just Spain - there are cheap flights to many other EU destinations where tobacco is much cheaper than in the UK.

Burden of proof

In a recent change in customs policy, the government increased the number of cigarettes that could be brought into the UK for personal use from another EU country to 3,200.

But that figure is only a guideline and the onus is now on the customs officer to prove the cigarettes are not for resale.

But if records show you travel regularly, the burden of proof shifts - a tool vital to the customs.

A customs spokesman in Belfast said: "Anyone who is genuinely taking duty paid tobacco into the country has nothing to fear.

"But we will be paying particular attention to anyone who is taking in tobacco regularly and claiming it is for their personal use. They can expect to be scrutinised and will have to give a satisfactory explanation."

Tobacco smuggling grew so rapidly in the 1990s that by 2000-01, 20% of the cigarette market in the UK was illegal - at a cost of �3.5bn in lost revenue.

That figure is expected to show another increase when the latest statistics are published.