There has been a sharp rise in the number of people caught trying to smuggle swallowed packages of cocaine into Northern Ireland.
An x-ray photo shows drug packages inside a smuggler's bowel
Already this year the number of such cases has hit double figures. In most instances those who have been caught have flown to NI from Amsterdam.
In two separate cases before the courts in February, two Dutch nationals were each jailed for six years for smuggling more than 100 packages of cocaine into Belfast International Airport, while another man from the same country was jailed for four-and-a-half years in March.
On Tuesday, David Ugochukwu, 31, from Blarney Street, Cork, was jailed for five years after being caught with swallowed 46 packages.
John Whiting, assistant director of criminal investigation at HM Revenue and Customs, said those being used as drugs mules were often the most vulnerable people in society.
"Many of them are of African descent living in Amsterdam and they really don't have much of a life there," Mr Whiting said.
"They're paid a relative pittance to carry out this pretty gruesome activity of swallowing up to 100 condoms full of cocaine for the journey and actually very seriously put their own lives at risk.
"All it needs is for one of these condoms to split."
Gerda Lienga, who was jailed after swallowing 110 packages of cocaine
In September 2006, a 40-year-old Welsh woman died after some of the 34 bags of cocaine she had smuggled from Trinidad burst in her stomach.
Mr Whiting said although some of the drugs are undoubtedly set for sale on Northern Ireland's streets, some may also be destined for south of the border.
"There are issues in terms of whether the market is entirely Northern Ireland or is it partly the Republic and in particular Dublin," he said.
"It may be that their view is 'we want to try a number of options in terms of we're not always going to use Dublin as an airport, we'll use Belfast as well'."
It is believed that some of the illegal drugs sold in Northern Ireland are smuggled from Europe to Great Britain, then sold by British crime gangs to suppliers in NI and the Republic.
"In these instances the criminal gangs in Ireland are sort of taking out the middleman," Mr Whiting said.
"So there will undoubtedly be a number of criminal gangs who are taking receipt of the drugs from these mules when they successfully breach our controls."
Much of the cocaine is being brought to NI from Amsterdam
As well as using intelligence information, customs officers, who have been working with the UK Border Agency, also profile travellers to see if they have legitimate reasons for coming to Northern Ireland.
"Many of the people that we've intercepted arrive in Belfast with nothing - they don't have a suitcase, they don't have money, they've got a mobile phone - and to be honest in many ways they stick out like a sore thumb," Mr Whiting said.
In one recent case the cocaine which was smuggled into Northern Ireland was found to be almost 100% pure - something which hasn't happened anywhere else in the UK in the last six to nine months.
This could be a real risk to drug-users used to taking cocaine which is of much lesser purity.
Mr Whiting said despite the rise in the number of cases, not all the would-be mules are able to swallow the drugs packages.
"Some of them can't do it, we did catch one guy who couldn't swallow them and had them in his baggage," he said.