(Reuters) -Ukraine will host a meeting of leaders of the so-called "coalition of the willing" on Saturday, President Volodymyr Zelenskiy said.

Established earlier this year and led by France and Britain, the coalition reflects concern among Europeans that the U.S. no longer represents a bulwark of support for Ukraine's three-year-old battle against a full-blown Russian invasion.

"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 U.S. 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 U.S. 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, but earlier this week Germany's new chancellor Friedrich Merz said he intended to visit Ukraine in the near future.

French President Emmanuel Macron said on Friday that France would take part in a meeting in Ukraine on Saturday. He also said that the meeting would be partly by video and partly via physical presence for participants.

(Reporting by Yuliia Dysa; editing by Hugh Lawson and Mark Heinrich)