THE Kremlin declined to comment on Monday on a Wall Street Journal report that Washington had held undisclosed talks with top Russian officials about avoiding further escalation in the Ukraine war.

According to the report, U.S. National Security Advisor Jake Sullivan held talks with aides to President Vladimir Putin in the hope of reducing the risk that the war in Ukraine spills over or escalates into a nuclear conflict.

"We have nothing to say about this publication," Kremlin spokesman Dmitry Peskov told reporters.

He also declined to comment on a Washington Post report that the United States has been privately encouraging Ukraine to signal it is open to talks with Russia, after Ukrainian President Volodymyr Zelenskiy ruled out negotiations while Putin is in power.

"Well, we don't know if that's the case or not," said Peskov.

"Once again I repeat that there are some truthful reports, but for the most part there are reports that are pure speculation," he said.

He added that while Russia remains "open" to talks, it is unable to negotiate with Kyiv due to the latter's refusal to hold talks with Russia.

Few high-level contacts between U.S. and Russian officials have been made public in recent months as Washington has insisted that any talks on ending the war in Ukraine be held between Moscow and Kyiv.