The Criminal Assets Bureau had its busiest year on record last year, according to its annual report.
It shows that almost €8.4 million in assets were frozen by the High Court last year, on foot of work carried out by the CAB.
The bureau also initiated 30 cases in the High Court, which is the highest number of new cases since it was established 23 years ago.
The report shows that over €5.6m was returned to the Exchequer last year. It included €6m in cash and bank accounts, over €2m in property and €113,000 in jewellery.
The report said CAB now has 99 new asset profilers across the country, who are trained in identifying potential targets. It brings to 378 the total number of profilers.
There are now 973 criminals under investigation by CAB, with 177 of those based in the Dublin metropolitan region west, the highest number of any garda division in the country.
There are 110 targets based in the DMR south division, followed by DMR north, where there are 80 known targets.
Outside of Dublin, Limerick has 72 targets, Wexford and Meath have 40, while there are 38 in Kildare.
In the annual report, CAB noted that additional staff are being sought from the Chief State Solicitor's Office to cope with the higher workload.
Other highlights of the report include €1.1m seized from a fuel laundering enterprise in Co Louth, on conclusion of proceedings taken by CAB.
The CAB investigation focused on the assets and activities of two families who were suspected to be involved in fuel laundering and the laundering of money derived from that criminal activity.
The investigation specifically looked at companies used and controlled by an organised crime gang to purchase large quantities of green diesel from oil companies.
The green diesel was then laundered and sold on as road diesel by "buffer companies", also controlled by the organised crime gang.
Following the conclusion of the bureau's proceedings in 2018, the total amount of money seized by the bureau from this fuel laundering enterprise amounts to €1.1m.
The bureau was set up in the wake of the murder of journalist Veronica Guerin in 1996. It is tasked with targeting assets obtained directly, or indirectly, from criminal conduct.
The agency has the power to seize assets if officers believe they are the proceeds of crime.
Minister for Justice Charlie Flanagan has welcomed the report and the particular emphasis placed by CAB on targetting organised crime gangs engaged in serious and organised "property crime" including aggravated burglaries.