US President Joe Biden held a 62-minute phone call with Russian President Vladimir Putin Saturday as the US warned a Russian invasion of Ukraine was imminent.

Biden told his counterpart that America and its allies would “respond decisively and impose swift and severe costs” if Russia attacked Ukraine, according to the White House transcripts of the conversation.

"While the United States remains prepared to engage in diplomacy, in full coordination with our allies and partners, we are equally prepared for other scenarios,” Biden said.

Biden warned that a Russian invasion would “produce widespread human suffering and diminish Russia’s standing.”

Tensions between Russia and Ukraine have mounted in recent weeks, after Russia amassed tens of thousands of troops on its border with Ukraine.

US Secretary of State Antony Blinken warned on Friday that Russia could launch an invasion of Ukraine at any time, including during the Beijing Winter Olympics.

Blinken said Washington was continuing to "draw down" its embassy in Ukraine and repeated a State Department call to American citizens in Ukraine to leave the country immediately.

"Simply put, we continue to see very troubling signs of Russian escalation, including new forces arriving at the Ukrainian border," Blinken told a news conference in the Australian city of Melbourne, as quoted by Reuters.

"As we've said before, we're in a window when an invasion could begin at any time, and to be clear, that includes during the Olympics," he added.

"We will continue that process and we've also been very clear that any American citizens who remain in Ukraine should leave now," Blinken said.

On Saturday, Israeli Prime Minister Naftali Bennett and Foreign Minister Yair Lapid called Israeli citizens in Ukraine to "immediately leave" in response to concerns that a Russian invasion was imminent.