Ukraine's President Volodymyr Zelensky is expected to travel to the US in the coming days, after Washington and Kyiv agreed to terms on a deal over natural resources and reconstruction, sources with knowledge of the matter said on Tuesday.

Negotiations have been ongoing for days over a deal that could grant the United States access to Ukraine's rare earth minerals as part of wider negotiations to end Russia's special military operation, as well as US involvement in a reconstruction fund for Ukraine.

CNN quoted a Ukrainian official as saying that terms were agreed upon after "everything unacceptable was taken out of the text and it is now more clearly spelled out how this agreement will contribute to Ukraine's security and peace".

Details of the agreement are not yet known, but a major sticking point was a demand from the Donald Trump administration for a $500 billion share of Ukraine's rare earth and other minerals in exchange for the aid the US had provided to Kyiv, which was previously rejected by Zelensky.

A source familiar with the contents of the draft agreement said it does not specify any US security guarantees or continued flow of weapons, but that the US wants Ukraine to be "free, sovereign and secure".

One of the sources familiar with the deal said future weapons shipments are still being discussed between Washington and Kyiv.

The US has not confirmed whether the terms of a deal have been agreed upon.

"I hear that (Zelensky is) coming on Friday," Trump said on Tuesday. "Certainly it's OK with me if he'd like to, and he would like to sign it together with me. And I understand that's a big deal, very big deal."

Asked what Ukraine would receive in the minerals deal, Trump said," $350 billion and lots of equipment, military equipment, and the right to fight on.

"We've pretty much negotiated our deal on rare earth and various other things," Trump told reporters, adding that "we'll be looking to" future security for Ukraine "later on".

"I don't think that's going to be a problem," he said. "I spoke with Russia about it. They didn't seem to have a problem with it. So I think they understand … once we do this, they're not going back in."

Some European countries have said they would be willing to send peacekeeping forces to Ukraine. Trump said on Monday that Moscow would accept such peacekeepers, but the Kremlin denied that on Tuesday.

Under the terms of a draft minerals agreement, according to sources familiar with its contents, the US and Ukraine would establish a Reconstruction Investment Fund to collect and reinvest revenues from Ukrainian sources, including minerals, hydrocarbons and other extractable materials.

Kyiv would contribute 50 percent of the revenues to the fund, minus operating expenses, and continue until the contributions reach a sum of $500 billion. The US would provide a long-term financial commitment to the development of a "stable and economically prosperous Ukraine".

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