Established earlier this year and led by France and Britain, the coalition reflects concern among Europeans that the US no longer represents a bulwark of support for Ukraine's three-year-old battle against a full-blown Russian invasion.
Military officers from around 30 countries have been involved in drawing up plans for the coalition which would provide a peacekeeping force in the event of a ceasefire being agreed between Russia and Ukraine.
"We need this coalition, and it should be strong enough to guarantee security in line with our common vision," Zelenskiy said in a video address published by his office in Kyiv.
Progress on what role Europe might play in providing post-war security guarantees is proving difficult with the prospect of a ceasefire distant and much dependent on how Russia responds and to what extent the US would support its allies.
Ukraine is seeking clear security guarantees from allies to safeguard it against any future Russian military action.
The coalition has been mulling the possibility of a limited foreign contingent deployment to Ukraine as part of possible guarantees.
Zelenskiy said on Thursday he had told US President Donald Trump in a telephone call that a 30-day ceasefire was a "real indicator" of progress towards peace with Russia, and Kyiv was ready to implement it immediately.
A 30-day ceasefire was initially proposed by Trump in March and Ukraine agreed, while Russia said such a measure could only take effect once reliable measures of monitoring and upholding it were put in place.
Zelenskiy did not specify which of the leaders was going to come to Kyiv for the coalition meeting on Saturday, but earlier this week Germany's new chancellor Friedrich Merz said he intended to visit Ukraine in the near future.
French President Emmanuel Macron will participate in the meeting.
Downing Street would not confirm whether British leader Keir Starmer planned to attend.
Starmer was present at the Oslo summit when Zelenskiy made the announcement, and later told broadcasters the "absolute focus" of leaders was on supporting Ukraine.
Meanwhile, Russia has unilaterally declared a three-day ceasefire running from May 8-10 to coincide with the 80th anniversary of the end of the Second World War.
Trump on Thursday called for a 30-day unconditional ceasefire between Russia and Ukraine, warning that Washington and its partners would impose further sanctions if the ceasefire was not respected.
Ukraine has expressed readiness to accept the US proposal.
On the ground, both sides reported fighting.
Ukrainian troops have made further attempts to breach the Russian border in the Kursk and Belgorod regions, according to the Russian Defence Ministry, while Ukraine's military said there had been 80 attacks by Russian troops along the front line on Friday.
with PA
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