US President Donald Trump on Sunday accused Ukraine again of lacking"gratitude" for Washington's support against Russia's invasion, as top US and Ukrainian representatives met in Geneva for talks on a proposal to halt the war.

"UKRAINE 'LEADERSHIP' HAS EXPRESSED ZERO GRATITUDE FOR OUR EFFORTS," Trump wrote on his Truth Social platform, while also re-airing frustration at the war's"HUMAN CATASTROPHE" and attacking his predecessor Joe Biden, but offering no direct condemnation of Moscow.

His comments came as US Secretary of State Marco Rubio was meeting with top Ukrainian officials in a wintery Geneva Sunday to discuss the US president's controversial 28-point plan for ending the nearly four-year conflict.

The Ukrainian delegation, headed by Andriy Yermak, also met with high-level officials from Britain, France and Germany in the Swiss city, as European countries scramble to have a seat at the table in the discussions.

Trump had given Ukraine until November 27 to approve the plan, but Kyiv wants changes to a draft that accepts a range of Russia's hardline demands, including requiring the invaded country to cede territory, cut its army and pledge never to join NATO.

German Chancellor Friedrich Merz on Sunday said he was"sceptical" a deal could be reached by that deadline.

The US president told reporters Saturday the proposal was not his final offer and he hoped to stop the fighting"one way or the other", raising hopes that it would be possible to strengthen Kyiv's position.

'Ukrainian perspectives' included

A US official, who asked not to be named, told AFP that a number of meetings were held throughout the day Sunday, with the US and Ukrainian delegation holding"detailed discussions about the peace agreement".

"It was productive and even conclusive in some areas," the official said, adding that a second round of talks underway at the US mission in Geneva aimed at"ironing out the details of the agreement".

By late Sunday afternoon, Ukrainian negotiator Rustem Umerov said the latest version of the US draft plan, which AFP has not seen,"already reflects most of Ukraine's key priorities".

Ukrainian President Volodymyr Zelensky also said on social media that the"American proposals may include a number of elements based on Ukrainian perspectives and critical for Ukrainian national interests", hailing that"diplomacy has been reinvigorated".

Recognise European 'centrality'

The US plan was drafted without input from Ukraine's European allies, who were striving Sunday to make their voices heard and boost Kyiv's position.

"Ukraine must have the freedom and sovereign right to choose its own destiny. They have chosen a European destiny," EU chief Ursula von der Leyen said in a statement, stressing that the"centrality" of the European Union's role must be "fully reflected" in any peace plan.

Ukraine's European allies gathered at the G20 summit in South Africa stressed that the US plan requires"additional work".

Finnish President Alexander Stubb told AFP that he and Italian leader Giorgia Meloni had called Trump early Sunday to discuss his Ukraine proposal.

"Of course, we discussed the situation, the 28-point plan, and some of the developments here in Johannesburg related to the peace plan," he said, declining to reveal the content of the discussions.

French President Emmanuel Macron told a news conference at the G20 that the plan contained points that had to be more broadly discussed as they concerned European allies, such as Ukraine's NATO ties and Russian frozen assets held in the EU.

He said the 30 countries in the"coalition of the willing" supporting Kyiv will hold a video call on Tuesday following the Geneva talks.

European Union countries were also planning to meet to discuss the Ukraine situation on the sidelines of a meeting with African leaders in Angola on Monday.

'Wish list'

Questions were meanwhile being raised over how much input Moscow may have had in drafting the original proposal, which was welcomed by the Kremlin.

Russian President Vladimir Putin has said the blueprint could"lay the foundation" for a final peace settlement, but threatened more land seizures if Ukraine walked away from negotiations.

Ahead of Sunday's talks, Washington insisted the Trump proposal was official US policy, denying claims by a group of US senators that Rubio told them the document was a Russian"wish list".

Rubio himself insisted on social media late Saturday that"the peace proposal was authored by the US".

"It is offered as a strong framework for ongoing negotiations. It is based on input from the Russian side. But it is also based on previous and ongoing input from Ukraine."

That did not calm all concerns.

"Together with the leaders of Europe, Canada and Japan, we have declared our readiness to work on the 28-point plan despite some reservations," Polish Prime Minister Donald Tusk said on X Sunday.

"However, before we start our work, it would be good to know for sure who is the author of the plan and where was it created."