Retailers have recorded a 58%increase in the volume of alcohol sales week on week this week, compared to this time last year.
Increases of between 22% and 30%t have been reported in earlier weeks of the Covid-19 restrictions.
It comes as a study in the UK found 20% of people say they are drinking more since the Covid-19 lockdown began.
Eunan McKinney, of Alcohol Action Ireland, says since the pubs closed it was inevitable there would be some increased buying but 58% is higher than expected.
"We don't know whether people are necessarily [drinking more]," he said.
"Obviously all pubs are closed and licensed premises are closed, therefore I suppose there may be some degree of displacement of activity. At 58% it certainly would be up and away and beyond [what was expected]."