A new Garda unit established to track the origins of cash found in drug searches, seized more than €2.2 million last year.
In a separate development, Customs officers attached to Revenue seized another €724,000 cash from criminals in 11 seizures during the year.
The financial investigations unit, which has been established within the Garda National Drug Unit (GNDU), has also identified assets valued at close to €3 million which it intends to confiscate in coming months.
The unit was established last year after the introduction of legislation which allowed gardaí to seize cash in any location in the State once they believed it was the proceeds of, or linked to, criminal activity.
Previously cash could only be seized at points of entry and exit to and from the Republic.
News of the new unit's establishment was revealed in The Irish Times late last year. It was set up following a marked increase in the frequency with which large sums of money were being found by officers carrying out searches for drugs.
In one case last year €400,000 in used notes was found during a search.
Senior Garda sources said the continued growth in the drugs trade and the much higher value of individual drugs shipments has given rise to drugs gangs using large sums of money to conduct their business.
"It was to be expected that some of these large sums would be found in properties linked to gang members," said one source.
During the course of 14 drugs searches by the GNDU last year, some €1.3 million in cash was discovered. The recent amendments to the Proceeds of Crime Act for the first time gave the Garda the power to seize the money.
These cases were then taken before the District Court where gardaí were granted permission to retain the funds ahead of final judgments by the courts.
In another case, members of the GNDU were granted permission by the High Court to transfer to State coffers some €500,000 seized under the new legislation. A further €397,000 found during a search was also transferred to the State when a drug dealer was convicted late last year.
Members of the unit have also identified property and cash on deposit valued at close to €3 million which they, in tandem with the Criminal Assets Bureau (Cab), intend to confiscate.
The assets were identified during the investigation of a gang importing large quantities of heroin into the State last year.
The move by GNDU to become more involved in tracing the origins of drugs money comes at a time when previously unheard of drug dealers are being arrested and are later found to have amassed considerable wealth unnoticed by the authorities.
When Keith Fitzsimons (24), from Glin Grove, Coolock, Dublin, was mistakenly shot dead in June, the chief suspect was found to have built a property portfolio of several million, despite being in his mid-20s and being relatively unknown to gardaí.
Gardaí are so worried about this pattern that members of the Cab are now regularly attending case conferences following gangland killings in an effort to identify any information which might help them seize the assets of those involved in gun crime.
Meanwhile, a 20-year-old man from Ballyfermot, Dublin, was being questioned by gardaí last night after heroin valued at €600,000 was found in his home late on Monday.
In Sligo, gardaí discovered cocaine valued at about €17,500 concealed in the grounds of Our Lady of Mercy Primary School on Pearse Road just after midnight yesterday morning.