US National Security Adviser Jake Sullivan has confirmed communication channels between Washington and Moscow remain open.

It comes as the White House refuses to deny reports that Mr Sullivan has been leading talks with Russia to prevent a nuclear escalation in Ukraine.

Speaking in New York, Mr Sullivan said it was "in the interests" of the US to maintain contact with the Kremlin.

Mr Sullivan has held confidential discussions with his Russian counterpart, Security Council secretary Nikolai Patrushev, and senior Kremlin foreign policy aide Yuri Ushakov

Senior officials told the paper the men had discussed ways to guard against the risk of nuclear escalation in the war in Ukraine, but had not any negotiations around ways to end the conflict.

Last month, Mr Sullivan said any use of nuclear weapons would have "catastrophic consequences for Russia".

He told the US broadcaster NBC that senior officials had "spelled out" the scope of the potential US response in private discussions with Russian officials.