Garda Commissioner Drew Harris has said there has been an increase in reports of domestic abuse, possession of drugs, possession of offensive weapons and fraud since Covid-19 restrictions came into effect in March.
Mr Harris said that criminals were making significant attempts to defraud individuals, institutions and "even government procurement operations".
Other crimes - such as theft, burglary and criminal damage - had "diminished" during the same period, he added. Mr Harris also said that there had been a worrying increase in domestic abuse – around 21% - compared to the same period last year.
The Commissioner was speaking during a public meeting with the Policing Authority, which is overseeing the Garda response to Covid-19.