The Garda Commissioner Martin Callinan says there are around 25 criminal gangs operating in Ireland.

Martin Callinan has told the Oireachtas Justice Committee that there is a gang working out of every Garda jurisdiction in the country.

But  he says most are centred in areas like Cork, Dublin, Limerick and Sligo.

He says Irish criminal organisations continue to forge links with international gangs particularly in Holland and Russia.

Drug trafficking is main catalyst 

Mr. Callinan said drug trafficking is the catalyst for almost all of the serious crime issues in Ireland.

The Commissioner says it is difficult to say how many people are involved in organised crime.

"For instance, you could have a particular group involved in conducting armed robberies and their  specialisation is armed robberies for the purpose of procuring cash maybe to buy drugs or whatever" he said.

"And they might farm out certain duties, i.e. stealing cars, or other specialisation to other criminals further down the food chain".

"And they cross-over - so it"s particularly difficult to try and put numbers on these people" he added.