EU country leaders will discuss how to step up support for Ukraine and their joint next steps to tame soaring energy prices when they meet on Friday.
In a meeting invitation letter to EU leaders published on Sunday, European Council President Charles Michel called for a firm EU response to recent developments, including Russia declaring the annexation of four regions of Ukraine on Friday.
"At our meeting we will discuss how to continue providing strong economic, military, political and financial support to Ukraine for as long as it takes," said Michel, who chairs meetings of EU country leaders.
Russia's proclaimed annexation came after Moscow held what it called referendums in occupied areas of Ukraine. Western governments and Kyiv said the votes breached international law and were coercive and non-representative.
The EU leaders' gathering in Prague will also produce guidance to Brussels on the next steps the EU should take to address soaring energy prices, Michel said.
"Our primary objective is to ensure that we guarantee security of supply and affordable energy for our households and businesses, particularly as the winter cold approaches," he said.
EU countries' energy ministers adopted a fresh set of policies on Friday to attempt to tame high energy costs, including windfall profit taxes on energy firms.
But states are divided over what to do next - with many calling for an EU-wide cap on gas prices, but others, including Europe's economic powerhouse Germany, opposed.
Leaders will also discuss on Friday how to protect their critical infrastructure. Unexplained ruptures last week in the Nord Stream pipelines in the Baltic sea, designed to bring gas from Russia to Europe, have promtped some countries to send in the military to secure potentially vulnerable energy systems.
(Reporting by Kate Abnett; Editing by Nick Macfie)