European Council chief Charles Michel said in a statement that the meeting in the Czech capital would focus on "the three most pressing - and interlinked - issues for us all, namely Russia’s war in Ukraine, energy and the economic situation."
"The war in Ukraine continues to rage," Michel said. "Regrettably the Kremlin has taken irresponsible escalatory steps: it has organised a national mobilisation campaign, sham coercive 'referenda' and the illegal annexation of Ukraine’s territories, and it pursues its threatening rhetoric."
He added: "In light of these developments, we must stand united and firm in our response. Our solidarity with Ukraine and its people remains unwavering. We will continue to strengthen our restrictive measures to further increase pressure on Russia to end its war."
The meeting on Thursday and Friday will also "discuss how to continue providing strong economic, military, political and financial support to Ukraine for as long as it takes," according to Michel.
"We will also examine how best to protect our critical infrastructure," he announced.
EU condemns 'illegal annexation by Russia' of four Ukrainian regions
The 27 EU national leaders last Friday condemned the Kremlin’s annexation of four Ukrainian regions in a joint declaration.
They said: “We firmly reject and unequivocally condemn the illegal annexation by Russia of Ukraine's Donetsk, Luhansk, Zaporizhzhia and Kherson regions.”
European Commission President Ursula von der Leyen said in a tweet: “All territories illegally occupied by Russian invaders are Ukrainian land and will always be part of this sovereign nation.”
Earlier that day, Putin signed documents to incorporate the four regions of Ukraine into Russia at a televised ceremony in the Kremlin.
The move came after Russia held what it called referendums in occupied areas of Ukraine and declared the annexation of the Donetsk, Luhansk, Zaporizhzhia and Kherson regions.
Monday is day 222 of the Russian invasion of Ukraine.
Source: PAP, consilium.europa.eu