RUSSIA's invasion of Ukraine could spark an international migration crisis of unprecedented scale prompting EU countries to prepare for the worst.
Central European countries on Thursday condemned Russia's attack on Ukraine and Poland called it a "barbaric act of aggression" while calling for "the harshest possible sanctions" against Russia and the Czech foreign minister.
All NATO allies that share borders with Ukraine except the countries of the eastern side of the European Union, the Czech Republic and Bulgaria, have also begun preparations to receive potentially hundreds of thousands of people fleeing Ukraine.
"We must immediately respond to Russia's criminal invasion of Ukraine. Europe and the free world must stop Putin. Today's European Council must approve the fiercest possible sanctions," Polish Prime Minister Morawiecki said.
A government spokesman said the Polish government expected a decision on strengthening NATO's eastern flank after Russian forces invaded Ukraine.
Czech Prime Minister Petr Fiala said on Twitter that the Russian invasion of Ukraine was an "absolutely unfair act of aggression towards an independent country that cannot live without the response of the EU and NATO."
Czech Foreign Minister Jan Lipavski also added on Twitter: "Together with allies, we will respond to this barbaric act of aggression."
Refugee International President Eric Schwartz warned that a refugee crisis triggered by Russia's attacks could be bigger than anything Europe has seen in decades.
He added: "Russia is creating a crisis that could risk displacement and suffering on a scale that may surpass any scene in Europe in decades."
Finland is also ready to receive refugees from Ukraine, Finnish Prime Minister Sanna Marin said on Thursday, as she strongly condemned Russia's military action in Ukraine.
Ms Marin speculated that a large number of refugees from Ukraine could try to flee to the European Union.
"The (Finland) interior ministry for its part is preparing to receive refugees from Ukraine," she told reporters.
Both Marin and Finnish President Souli Niinisto strongly condemned Russia's attack on Ukraine.
"Despite prior warnings, this morning has come as a shock to all of us and our deepest feelings are with the people of Ukraine," Mr Ninisto said.
Mr Niinisto ruled out the possibility of Finland's reaction to the events by immediately applying for NATO membership.
"(In Finland) we are now looking at quick comments to apply today and join tomorrow. These sensitive responses are understandable but may not really work in the real world."
Romania said it was preparing to receive half a million potential refugees from Ukraine in case of a Russian invasion.
The UN refugee agency said on Tuesday that it had not seen an increasing movement of people fleeing Ukraine, but Eastern European governments and cities near the Ukrainian border were preparing to move in if needed.
Romanian Defense Minister Vasile Dinacu said on Tuesday, "There are many estimates, but we can receive more than 500,000 refugees, that is, ... for which we have prepared with the Ministry of the Interior and other institutions."
"A plan has been prepared for all the big cities, for this there are areas near the borders."
Romania, a European Union and NATO member state, has a 600-kilometre (370 mi) border with Ukraine, but saw relatively few Ukrainian refugees after Russia's annexation of Crimea in 2014.
“We are also not expecting a big influx here now, but one never knows,” said Mr. Dinku.
German Interior Minister Nancy Fesser said today that Germany will provide aid to countries in Eastern Europe, especially Poland, which are facing an influx of refugees from the conflict in Ukraine.
She said: "We will offer massive support to the affected states, especially our neighbor Poland, in the event of large refugee movements."
He added that German security officials have taken protective measures against possible cyber attacks.
US Ambassador to the United Nations Linda Thomas-Greenfield warned that up to five million people could be displaced by the conflict.
She added: "If Russia continues on this path, according to our estimates, it could lead to a new refugee crisis, one of the largest facing the world today."