A high-level US delegation meets in Rome Monday with a top Chinese official, the White House said as it warned Beijing would face severe "consequences" if it helps Russia evade sanctions over its war in Ukraine.

National Security Advisor Jake Sullivan and Yang Jiechi, the Chinese Communist Party's chief diplomat, "will discuss ongoing efforts to manage the competition between our two countries and discuss the impact of Russia's war against Ukraine on regional and global security," National Security Council spokesperson Emily Horne said Sunday in a statement.

Beijing has declined to directly condemn Moscow for launching its invasion, and has repeatedly blamed NATO's "eastward expansion" for worsening tensions between Russia and Ukraine, echoing the Kremlin's prime security grievance.

Sullivan made a round of Sunday talk shows to say the White House was "watching closely" to see whether China provides material or economic support to Russia to help it evade the punishing impact of sanctions.

"It is a concern of ours, and we have communicated to Beijing that we will not stand by and allow any country to compensate Russia for its losses from the economic sanctions," he said on CNN show "State of the Union."

Sullivan said that while he did not wish to "brandish threats" against major economic rival China, "we are communicating directly, privately to Beijing that there will absolutely be consequences for large-scale sanctions-evasion efforts."

Beijing said this past week that its friendship with Russia remains "rock solid" despite international condemnation of Moscow, and has expressed an openness to help mediate an end to the war.