US President Donald Trump accused the Ukrainian president of “trying to back out” of the minerals deal expected to be agreed between the two countries as early as this week, adding that Volodymyr Zelensky would face “big problems” if he didn’t sign an agreement. But Ukraine has highlighted that the conditions of the deal changed significantly in recent days.

Russia and the United States have started talks on joint rare earth metals and other projects in Russia, and some companies have already expressed an interest in them, President Vladimir Putin's investment envoy said in remarks published on Monday.

Amid efforts by U.S. President Donald Trump to end the war in Ukraine, minerals cooperation has been floated by both Kyiv and Moscow, though Trump said on Sunday that Ukrainian President Volodymyr Zelenskiy wants to back out of a proposed deal.

The terms of a mineral deal between Ukraine and the U.S. have not yet been finalised, Ukrainian officials said on Friday, after a summary of Washington's latest offer suggested it was demanding all of Ukraine's natural resources income for years.

The latest U.S. proposal would require Kyiv to send Washington all profit from a fund controlling Ukrainian resources until Ukraine had repaid all American wartime aid, plus interest, according to the summary, reviewed by Reuters.