Russia said Thursday it hopes for "contact" between Kremlin chief Vladimir Putin and US President Joe Biden in the coming days, as tensions over the Ukraine conflict skyrocket.

The comments come after the US and Russian foreign ministers met in Sweden to discuss allegations raised by Kiev and its Western allies that Russia could invade ex-Soviet Ukraine this winter.

"The date has not yet been agreed. There are difficulties in aligning the calendars of the two leaders, but contact is very necessary, our problems are multiplying," Deputy Foreign Minister Sergei Ryabkov said.

"There is no movement on bilateral affairs, which are more and more reaching an acute crisis phase. There is no mutual understanding about how to de-escalate the situation in Europe," he was quoted as saying by Russian news agencies. 

"The situation in Europe is very alarming," he added. "It's clear that this will be one of the main topics of discussion at the presidential level."

Tensions have escalated in recent weeks after the West claimed Russia had built up troops around Ukraine, on Crimea -- which Moscow seized in 2014 -- and in two eastern regions held by pro-Russian rebels.

The Kremlin has denied the allegations and accused Washington of whipping up hysteria.

Despite increased contacts between the two rivals since Putin and Biden met for the first time at a summit in Geneva in June, tensions have remained high.

As well as the Ukraine conflict, Russia and the United States continue to argue over cyberattacks and the staffing of their embassies, after several waves of diplomatic expulsions.