ANKARA (Reuters) -President Volodymyr Zelenskiy was quoted on Wednesday as saying a U.S. proposal for a critical minerals deal was unfair as it did not include security guarantees, and he did not want Ukraine to become a hub for raw materials.

Last week Kyiv sent Washington a revised draft of an accord that could open up its vast resources of critical minerals to U.S. investment in order to help win U.S. support, amid concerns in Kyiv over an earlier U.S. version.

"I said 'this document is not ready, we will not sign this. You continue to work on this document," Zelenskiy was quoted as telling some Turkish media after talks in Ankara on Tuesday.

"I am always open to you investing in our country, in our natural resources... But if we are to give something, we have to receive something," he was quoted as saying by state-owned Anadolu news agency.

"We don't want to become a centre of raw materials for any continent."

Zelenskiy had set out the contours of the deal in a Reuters interview this month. The minerals in question would include rare earth varieties, as well as titanium, uranium and lithium among others.

U.S. President Donald Trump, who has not committed to continuing vital military assistance to Ukraine, has said he wants $500 billion in rare earth minerals from Kyiv and that Washington's support needs to be "secured".

Zelenskiy's visit to Ankara coincided with a meeting between U.S. and Russian officials in Riyadh, without Ukrainians, over the war in Ukraine.

Zelenskiy said he believed Ukraine had support in Washington but that he wanted to see more backing from Trump.

"We see (the U.S.) have removed Putin from his political isolation, but that is their own decision. But when you say 'these are our plans to end the war', this raises questions for us. Where are we? Where on the negotiating table are we? This war is taking place inside Ukraine," he said.

"There should be people at the negotiating table who can stop (Russian President Vladimir) Putin if he wants to return to war. And they must be able to give us real - not just promises - and concrete security guarantees. We are ready for such a dialogue," he was quoted as saying.