Gardai are working alongside Interpol and European police forces to identify a number of Irish nationals who they suspect have been trained by former special forces in Croatia, Serbia, Slovakia and possibly Romania.

Several members of one north Dublin gang suspected of involvement in tiger robberies — which involve kidnapping bank personnel with access to large sums of money — have availed of private military training.

Intelligence available to Crime and Security, the force’s intelligence department, indicates that gangs from Finglas and Coolock were trained in the use of military firearms and surveillance while attending a bodyguarding course in eastern Europe. They enrolled on the private military courses using the internet.

“A handful of suspects have attended bodyguarding and weapons courses taught by former commandos in the eastern bloc. These courses are usually offered to people who want to become bodyguards. They teach everything from how to use guns to counter-surveillance. Some courses train students in how to deal with armed confrontations,” said one security source.

“In this case, they are effectively training for kidnappings and armed robberies, and the day when they will encounter an armed response unit.”

Detectives have long suspected that certain criminals had received military or special-forces training. Kidnap victims taken in recent tiger raids have told investigating gardai that raiders operated in a military-style fashion and didn’t seem to panic when confronted with problems.

One witness described her captors as operating in such cohesion that she likened them to a Swat team. Other kidnap victims have made statements saying their captors worked as a close unit and were notably polite to them.

Another feature in several of the raids was the absence of CCTV footage of the suspects, leading detectives to conclude the culprits had been trained in counter-surveillance.

Gang members have also shown themselves to be more than adept at departing from crime scenes without leaving DNA traces.

The suspicion that Irish criminals have received firearms training poses a serious problem for specialist garda teams like the elite emergency response unit, which is tasked with combating armed gangs. It has also forced gardai to re-evaluate the threat posed by some gangs in the Dublin region.

Gardai believe the criminals enrolled on courses by booking over the internet. Private firearms and bodyguarding courses are advertised widely on the internet and in security publications.

Course attendance fees range from €4,000 to €25,000 depending on the tuition provided. Former commandos retired from the Croatian and Serbian armies act as course tutors. There is no indication that the course operators are aware of the ultimate intentions of their clients.

Modules for most courses include firearms instruction, counter-surveillance and siege situations. Students are also permitted to use a variety of weapons including Uzi submachine guns and semi-automatic revolvers while being drilled in firearms and shooting techniques.

There have been about ten tiger kidnapping in the past ten months, netting a few gangs in excess of €2.5m. Among the high-profile raids was the theft of €800,000 from the Permanent TSB in Coolock, Dublin.

A gang held the manager’s family hostage overnight before forcing her to hand over the cash.

Michael McDowell, the justice minister, has warned banks against co-operating with kidnappers. McDowell has told financial institutions that if they pay a ransom to gangs involved in tiger robbery kidnappings, they are endangering people’s lives.

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