U.S. national security adviser Jake Sullivan spoke on Wednesday with Nikolay Patrushev, the secretary of Russia's Security Council, and warned him about the consequences "of any possible Russian decision to use chemical or biological weapons in Ukraine," the White House said.

Sullivan told Patrushev that if Russia was serious about diplomacy, then it should stop attacking Ukrainian cities and towns, the White House said in a statement.

(Reporting by Kanishka Singh in Bengaluru, Editing by Chris Gallagher)