The Taoiseach has accused the Russian president of committing war crimes after unleashing an “unprovoked and unjustifiable war” on Ukraine.
Micheal Martin branded Vladimir Putin a “bully and a thug” in the Dail.
The Fianna Fail leader said Ireland must be “very generous” in helping Ukrainian refugees fleeing the fighting.
He also told the Dail Putin has “fundamentally altered” the multilateral rules-based order since the end of the Cold War.
“No one in this House or anywhere else should be under any illusions about the seriousness of the situation that Europe and the world faces right now this afternoon,” Mr Martin said.
“Vladimir Putin, a bully and a thug, has unleashed an unprovoked and unjustifiable war on the people of Ukraine, committing war crimes in the process – as we are witnessing.
“As (Ukrainian ) President (Volodymyr) Zelenskyy said, most movingly to the European Parliament this morning, every day now in Ukraine is someone’s last day.
“I was very struck by both the contribution he made there and indeed to the European heads of state last Thursday at the EU council.”
He added: “The biggest challenge facing us as a country, I believe, is that we must be very, very generous in terms of the refugee crisis that will undoubtedly flow as a result of this war.
I believe Putin has fundamentally altered the multilateral rules-based order that characterized international behaviour since the end of the cold war, it's that fundamental.
“It will be beyond anything that we’ve comprehended before. I’ve said to my colleagues in government and to the departments: we must put to one side what we might have considered to be the norms in terms of responding in a humanitarian way to the plight of the Ukrainian people.
“I believe Putin has fundamentally altered the multilateral rules-based order that characterized international behaviour since the end of the cold war, it’s that fundamental.”
Sinn Fein leader Mary Lou McDonald condemned “unreservedly” the Russian invasion and offered Ukrainians her party’s “total and unwavering solidarity” at “this deeply disturbing and traumatic time for their country”.
She said the invasion is a “criminal affront to the civilized world and a threat to the peace and security of people everywhere”.
She added: “The Irish people have been appalled at the heart-breaking scenes of civilians being killed, being injured and fleeing their homes for their lives.
“We are united in our condemnation of the actions of the Russian President Vladimir Putin.
“Any attempt by Putin or his regime to justify his actions as a response to Nato are without foundation and are merely a means of distraction from his own culpability.”
Co-leader of the Social Democrats Catherine Murphy said Ireland has been slow to act against the Russians in the past.
Referring to a Government decision to block planning permission for an extension to the Russian Embassy in 2020, she added: “It has long been reported in relation to the Russian Embassy in Dublin, which have been used as a base for espionage operations across Europe.
“This was confirmed when the Government used legislation to block a proposed expansion of the Embassy on security grounds in 2020.
“Yesterday, (Minister for Foreign Affairs) Simon Coveney suggested that the Russian diplomats or some operatives that are in Ireland, who may not be diplomats, could be expelled in coming days.
“Can you confirm to the House whether this means that the Government have identified spies among the Russian embassy staff that are about to be expelled?”
Mr Martin did not directly answer, instead saying no country is proposing to expel any Russian ambassador.
“Our view is that it is important, from a practical point of view, in looking after our citizens, either in Russia or Ukraine, that we keep our channels open,” he said.
“We have a limited presence in the embassy in Moscow – six individuals in total – and they have a fundamental function to look after Irish citizens in Russia and also to articulate our views, and to keep abreast of what’s happening within that jurisdiction, and different jurisdictions.”
