It is increasingly recognised by organised criminals as being a profitable enterprise

David Bolt, National Criminal Intelligence Service

But officers say they have no real idea of the extent of the problem because intelligence resources have been focused on drug smuggling.

David Bolt, head of the National Criminal Intelligence Service (NCIS), said the huge profits to be had from human trafficking were proving a powerful lure for organised crime.

His stark assessment came on the day home secretary David Blunkett outlined tough new measures to clamp down on abuses of Britain's asylum system.

'Early stages'

Last year's annual assessment of the threat posed to the UK by organised crime suggested just 3% of known criminal gangs were principally concerned with smuggling people, Mr Bolt said.

That figure is expected to remain static when the latest figures are published in July, he said.

But the real figure could be far higher as NCIS and other agencies, such as the National Crime Squad, have little idea of the true extent of the problem.

Giving evidence to the Lords' Home Affairs Committee, Mr Bolt said: "We are still, in terms of illegal immigration crime, at an early stage in the organisation of a response.

"Much of the data that we collect about organised crime concerns drugs, particularly class A drugs.

"It is perhaps no surprise that we see most of the groups that are being targeted by law enforcement as being involved in primarily Class A drugs."

'Understating the problem'

He said it would take a little more "evolution" of NCIS's "attack against organised crime before we see a genuine figure for groups that are involved in that particular activity."

"So we see 8, 9, 10% at the moment, but I suspect that figure is actually understating the problem," he added.

He said he "wouldn't like to hazard a guess at the true size of the problem" but he believed it was "significantly larger" than that.

"It is increasingly recognised by organised criminals as being a profitable enterprise and therefore it is likely that is also on the increase," Mr Bolt said.

'Potential risk'

Trevor Pearce, deputy director general of the National Crime Squad, dubbed Britain's answer to the FBI, agreed with Mr Bolt's assessment.

He said there was spare "capacity" for criminal gangs to muscle in on the illegal trade in people.

"Clearly there are still opportunities for some of those to move into the trafficking, the smuggling of people.

"I think we have to be very cognisant of the potential risk of increase as much as the current volume," Mr Pearce said.

Prostitution

Mr Bolt said the NCS was working with other agencies and its European counterparts, including Europol, to develop a "holistic" approach to the problem.

He called for the EU to fund a publicity campaign to warn potential illegal immigrants of the reality facing them when they arrive in the UK.

Women in particular were being lured to the country under false pretences and forced into prostitution.

Mr Bolt said gangs had even paid women to return to their home countries to tempt other victims with false tales of wealth.