Donald Trump has said that his 28-point peace plan for Ukraine is "by far" not the "final offer", ahead of crisis talks in Geneva.

Meeting on the sidelines of a G20 summit in South Africa, European and other Western leaders scrambled to respond to the US president's demand for Ukraine to accept the plan drawn up by the Trump administration and the Kremlin.

In a joint statement on Saturday, they said the plan, announced on Friday, could serve as a basis for talks to end Russia's war in Ukraine - but required "additional work".

Follow the latest on the Ukraine peace plan

As a result, a meeting has been hastily convened in Geneva, Switzerland, on Sunday, where national security advisers from the E3 - France, Britain and Germany - will meet EU, US and Ukrainian officials for further discussions.

Ahead of the talks, Volodymyr Zelenskyy said in a video address to his nation that Ukrainian representatives at the talks "know how to protect Ukrainian national interests and exactly what is needed to prevent Russia from carrying out" another invasion.

"Real peace is always based on security and justice," the Ukrainian leader added.

The 28-point peace plan closely resembles the list of demands repeatedly stated by the Kremlin since it launched its full-scale invasion of Ukraine nearly four years ago and if adopted, would see Ukraine cede territory to Russia - and cut the size of its military.

Mr Trump has said he wants a response from Ukraine by Thursday, while suggesting an extension could be possible.

On Saturday, Mr Trump told reporters outside the White House that the plan was not the "final offer" when asked.

He said: "We'd like to get the peace, it should've happened a long time ago. The Ukraine war with Russia should've never happened. If I was president, it would have never happened. We're trying to get it ended. One way or another, we have to get it ended."

His secretary of state Marco Rubio insisted that the peace proposal was authored by the US, despite what a handful of senators have alleged is a "Russian wish list".

"It is based on input from the Russian side. But it is also based on previous and ongoing input from Ukraine," Mr Rubio said.

Leaders have sought to balance praise for President Trump's attempt to end the war with recognition that some terms in his proposal are unpalatable for Kyiv.

"There are many things that cannot simply be an American proposal, which requires broader consultation," French President Emmanuel Macron said on the sidelines of the G20, adding that an agreement had to allow for peace for Ukrainians and "security for all Europeans".

German Chancellor Friedrich Merz underlined the importance to Europe of supporting Ukraine.

"If Ukraine loses this war and possibly collapses, it will have an impact on European politics as a whole, on the entire European continent. And that is why we are so committed to this issue," he said.

"There is currently an opportunity to end this war, but we are still quite a long way from a good outcome for everyone."

Prime Minister Sir Keir Starmer told reporters in Johannesburg: "We are concerned about [caps on military], because it's fundamental that Ukraine has to be able to defend itself if there's a ceasefire."

He said the proposal "requires additional work", adding: "And that's why there's been the agreement that in Geneva tomorrow [Sunday], you'll have senior US personnel, you'll have European NSAs [national security advisers], including the UK NSA, and obviously Ukrainians there to work further on the draft."

Sir Keir also spoke to Mr Trump, relaying discussions held at G20 to the US leader, according to a Downing Street spokesperson, who added that the two leaders would speak again on Sunday.

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Meanwhile, Sir Keir, who has defended his decision to fly to the G20 days before a difficult budget, said the role of the G20 is "critical at this moment".

"The G20 has worked together before to fix fundamental problems in the global economy. We need to find ways to play a constructive role again today in the face of the world challenges," he said.

"I'd like to see us come together around a five-point plan for growth that leaves no one behind."

The US, however, is boycotting the talks.

The Trump administration made its opposition to South Africa's G20 agenda clear earlier this year when the country started holding meetings ahead of the summit. South Africa gets to set the agenda as the country holding the rotating G20 presidency.

G20 leaders broke with tradition and adopted a declaration at the start of their summit - despite opposition from the US.

Vincent Magwenya, spokesman for South African president Cyril Ramaphosa, said a leaders' declaration was adopted unanimously in Johannesburg.

The White House later accused South Africa of refusing to facilitate a smooth transition of the G20 presidency.

The G20 bloc was formed in 1999 as a bridge between rich and poor nations to confront global financial crises.

While it often operates in the shadow of the powerful Group of Seven nations, G20 members represent around 85% of the world's economy, 75% of international trade and more than half the global population.

(c) Sky News 2025: Ukraine peace plan 'not final offer' Trump says, ahead of crisis talks in Geneva