Taoiseach Leo Varadkar said he believes some of the people who protested against planned refugee accommodation centres which were the subject of arson attacks need to be “held accountable for their silence”.
Labour leader Ivana Bacik said more than 20 properties across the country have been set alight in recent months.
Several buildings have been severely damaged in arson attacks after being identified, occasionally incorrectly, as selected for accommodating asylum seekers.
The Labour Party has described the arson attacks as a form of domestic terrorism.
Speaking in the Dail on Tuesday, Mr Varadkar said gardai expect to bring prosecutions in relation to the arson attacks.
The Taoiseach said there was a need for people to be convicted for the crimes, adding: “But I have to say it is deeply ironic that people who oppose migration, who connect migration with criminal activity are indeed the criminals themselves carrying out the very serious crime of arson.
“And I have to say while I think many protesters may very well be decent people and good people, I don’t believe that protesters who spent the entire day and the entire night outside a building didn’t see anything before the building burned down.
“And they need to be held accountable for their silence and complicitness, in my view.”