US President Donald Trump on Tuesday said a Ukraine-Russia deal is "very close," but European leaders were sceptical and Russian missiles continued to rain down on Kyiv.

Trump, visibly frustrated at his failure to make good on last year's election boast that he could quickly end the war, said "we're getting very close to a deal."

An initial US plan which was heavily weighted in Russia's favour has been replaced by one taking in more of Ukraine's interests.

A Ukrainian official said the new version was "significantly better."

However, US officials acknowledged that "delicate" issues remain.

And French President Emmanuel Macron threw cold water on the idea of a rapid solution, stating that there is "clearly no Russian willingness" for a ceasefire or to discuss the new, more Ukraine-friendly proposal.

Frantic discussions have been underway since the weekend when Ukrainian and US representatives huddled in Geneva to discuss Trump's controversial, initial 28-point plan for settling the bloody conflict.

Latest talks including US and Russian delegates were taking place in Abu Dhabi, US media reported.

Leaders of a group of 30 countries supporting Ukraine also met by video on Tuesday.

US negotiator Dan Driscoll emerged upbeat from a meeting with Russian counterparts, his spokesman saying: "The talks are going well and we remain optimistic."

The White House cited "tremendous progress," while cautioning "there are a few delicate but not insurmountable details that must be sorted out."

But the war, which began with Russia's full-scale assault on Ukraine in 2022, continued unabated.

Powerful explosions rocked Kyiv beginning around 1am (2300 GMT), as Russian drones and missiles rained down, setting fires in apartment buildings.

City officials said seven people were killed.

Thick smoke, turning red and orange in the blizzard of Ukrainian air defence fire, rose over the capital as residents fled underground into metro stations. (AFP)