Ukraine has agreed the terms of a major minerals deal with the US.
The BBC says no details have been provided.
Media reports say Washington has dropped initial demands for a right to US$500 billion in potential revenue from utilising the natural resources but has not given firm security guarantees to Ukraine.
US President Donald Trump said he was expecting his Ukrainian counterpart Volodymyr Zelensky in Washington to sign the deal this week, after the two leaders exchanged strong words about each other.
Without confirming that an agreement had been reached, Trump said on Tuesday that in return for the deal Ukraine would get “the right to fight on”.