European leaders are set to meet in South Africa to discuss alternatives to a U.S. plan to end Russia's war in Ukraine as a top Ukrainian delegation prepared for direct talks with Washington.

European and other Western leaders meeting on the sidelines of a G20 summit scrambled on Saturday to come up with a coordinated response to U.S. President Donald Trump's demand for Ukraine to accept his peace plan with Russia by Thursday.

A high-level U.S. military delegation arrived in Kyiv on Wednesday in a bid to revive the White House’s stalled push for an end to Russia's invasion.

The United States and Russia have drawn up a plan to end the bitter fighting in Ukraine, which would require major concessions from Kyiv.

The Trump administration has threatened to suspend aid to Ukraine unless its government accepts a peace framework by Thanksgiving. The loss of intelligence sharing by the US could prove more devastating than a cutoff of weapons.

Leaders from Europe, Canada and Japan say the plan needs "additional work" but includes elements "essential for a just and lasting peace".

Members of Congress attending an international security forum said Secretary of State Marco Rubio called them to say the Americans did not instigate the proposal.