A crackdown by gardaí and other state agencies on families involved in crime in Limerick has led to some central figures involved in criminality leaving the city and moving abroad.

"There has been sustained pressure on some of them, particularly the McCarthy-Dundons. So we've been sitting on them and raiding their houses. It's the only way to send out the message that it's not acceptable any longer; they don't run the show," said a senior garda source.

Members of the McCarthy-Dundon gang were responsible for the murder of innocent businessman Roy Collins in April and the mistaken-identity murder of rugby player Shane Geoghegan in November.

John Dundon (29), a key member of the gang, has been on the run since he failed to show up for a court appearance in November for using threatening and abusive behaviour, and has reportedly been living in London.

At least three other members of the gang have since joined him in the past four weeks.

"We don't know if they've gone on a holiday or gone away permanently. But they were not happy with how closely they were being monitored here," the garda added.

Members of the Keane-Collopy gang are also under garda scrutiny but not to the same extent as the McCarthy-Dundons, who are considered more powerful. "We do know that some of the people involved on the outskirts with this gang have left the area for the time being at least," he added.

A separate clampdown by a group of state agencies aimed at dramatically reducing the amount of organised crime in the city has also been targeting families involved in crime in Limerick.

Led by the Limerick Regeneration Agency, the initiative has identified the main families involved in anti-social behaviour and crime. A group of state agencies, including the gardaí, social welfare, the local authority and the HSE, have been working together to address the problems these families are creating.

The Criminal Assets Bureau (CAB) will be brought in to examine how some households claiming social welfare can afford to drive top-of-the-range cars. "Regeneration is about supporting the good, law-abiding people of Limerick, who are the vast majority. There has been a reduction in serious crime and anti-social behaviour since regeneration began," said Brendan Kenny, chief executive of Limerick's Regeneration Agency.

The agency has maintained that those involved in criminality will not be re-housed under the new plans if they do not qualify for a 'certificate of eligibility' from the local council, one reason some criminals are leaving the city.