European police intelligence agency Europol is drawing up a list of the top 100 criminal gangs in Europe.
Gardaí say at least nine major Irish gangs are operating across the continent with up to 40 criminals involved.
The Dutch national crime squad says the Netherlands is the European centre for heroin and cocaine trafficking and the manufacture of synthetic drugs.
Europe's police intelligence agency is situated in the city as many of the continent's most dangerous are operating from bases there.
A number of Irish detectives and customs officers are based in Europol sharing information and intelligence with 26 other European police forces.
The agency's director Rob Wainwright says criminals and criminal gangs are now becoming more sophisticated.
He believes they are diversifying into cyber crime, counterfeiting and money laundering and operating in smaller, looser criminal structures.
