President Joe Biden will offer President Vladimir Putin a "diplomatic path" out of tensions around Ukraine but remains "gravely" concerned by Russian troop movements, a senior US administration official said Wednesday.

In a phone call with Putin scheduled for Thursday, Biden will say "we are prepared for diplomacy and for a diplomatic path forward," the official told reporters.

"But we are also prepared to respond if Russia advances with a further invasion of Ukraine," Biden will tell Putin, the official said, adding that "we continue to be gravely concerned" by Russian forces near the Ukrainian border.

The phone call is taking place at the request of the Kremlin, the official said, speaking on condition of anonymity.

The two leaders will discuss a range of issues ahead of intensive diplomacy next month that will see Russian officials meet with US counterparts in Geneva on January 10. 

The Russians will then meet separately with NATO and the OSCE regional security body.

Despite the surge of diplomatic contacts, Washington considers that the Russians have to do more to reduce the threat level around Ukraine for significant progress to take place.

Russia deployed tens of thousands of combat troops to the border, prompting fears that the Kremlin is ready to order seizure of more Ukrainian territory. 

Although this has not happened, the force is "not entirely static," the official said and remains "a continuing source of great concern."

Washington "would like to see a return of forces to their regular training areas."

More broadly, the sabre rattling makes any deeper progress less likely, the official said.

"Getting to an end game, a diplomatic end game, getting to meaningful understanding between the US and Russia, NATO and Russia, Ukraine and Russia, that really only happens practically in an environment where we're seeing deescalation," the official said.

According to the official, there is no plan for another in-person Biden-Putin summit at the Geneva talks.

Biden will speak to Ukraine's President Volodymyr Zelensky "soon," although no date has been set, the official said.