On Tuesday and yesterday, Gardaí carried out raids in Dublin, Tipperary, Kerry and Offaly.
A total of €38,000 in cash was seized along with a large amount of computers and documents. In addition to residential properties, business premises were also raided.
It is believed two brothers from the midlands who ran businesses around the country were the targets of the Garda operation.
According to sources, the brothers have built up links with one of the main Limerick gangs and had been using their businesses to launder cash for them.
Meanwhile, up to 20 men linked to the Keane-Collopy and McCarthy-Dundon gangs have been arrested in wide-scale operations in Limerick in recent weeks. Some are in custody awaiting trial.
Last week, two brothers were jailed for a total of 14 years at Limerick Circuit Court after they were caught by the ERU after a high-speed chase. A gun they had collected was found in the car.
A member of the ERU received serious facial injuries when their car attempted to drive off.
Supt Frank O’Brien said Gardaí in Limerick were receiving all the resources required to tackle gang crime in the city.
He said: “The Garda Síochána are showing our determination to fight gang crime. There is confidence building in the community and people are prepared to come forward. “Communities are getting sick of small groups of people trying to dictate to them,” he said.