China is providing critical support that enables "Russia to keep that defense industrial base going, to keep the war machine going, to keep the war going. So that has to stop," Blinken told a joint news conference in Washington with NATO Secretary General Jens Stoltenberg.

Echoing remarks he made the previous day, Stoltenberg called for China to face "consequences" if it keeps backing Russia.

"China cannot have it both ways. They cannot continue to have normal trade relationships with countries in Europe and at the same time fuel the biggest war we have seen in Europe since the Second World War," Stoltenberg said.

Beijing presents itself as a neutral party in the Ukraine war and says it is not sending lethal assistance to either side, unlike the United States and other Western nations that have provided key military support to help Kyiv combat Moscow's invasion.

China and Russia's strategic partnership has only grown closer since Moscow launched the invasion in February 2022, with Beijing offering a critical lifeline to Russia's isolated economy.

Blinken and Stoltenberg also expressed concern about the strengthening of ties between Russia and North Korea.

Russian President Vladimir Putin is due to visit North Korea on Tuesday and Wednesday, and hailed Pyongyang ahead of his arrival for "firmly supporting" Moscow's war in Ukraine.