Ukrainian service members ride at a infantry fighting vehicle on the front line near the village of Zaitseve in the Donetsk region, Ukraine February 19, 2022. (REUTERS/Gleb Garanich)

"President Biden continues to monitor the evolving situation in Ukraine, and is being updated regularly about events on the ground by his national security team," White House Press Secretary Jen Psaki said in a statement. "They reaffirmed that Russia could launch an attack against Ukraine at any time."

Foreign ministers from the G7 group of rich nations said the same day they had seen no evidence Russia is reducing its military activity in the area and remained "gravely concerned" about the situation.

After Kyiv and Moscow traded accusations over new shelling near the border, France and Germany urged all or some of their citizens in Ukraine to leave. US Defense Secretary Lloyd Austin said Russian forces were beginning to "uncoil and move closer" to the border.

Russia ordered the military build-up while demanding NATO prevent Ukraine from ever joining the alliance but says Western warnings that it is planning to invade Ukraine are hysterical and dangerous. Moscow says it is pulling back.

G7 foreign ministers called on Russia to choose the path of diplomacy. "As a first step, we expect Russia to implement the announced reduction of its military activities along Ukraine's borders. We have seen no evidence of this reduction," they said in a statement.

Ukrainian President Volodymyr Zelenskiy said he had an "urgent" phone conversation with French President Emmanuel Macron and discussed possible ways of immediate de-escalation and political-diplomatic settlement. Macron is due to speak with Putin on Sunday. 

World Bank President David Malpass told Zelenskiy on Saturday the bank was readying funding to Ukraine of up to 350 million USD.