Ukraine's allies are holding a crucial meeting on Friday at the US air base in Ramstein, Germany, to coordinate further military aid to Kyiv.

Ahead of the talks, pressure has been growing on Berlin to approve the delivery of German-made Leopard 2 tanks, which are keenly sought after by officials in Kyiv to fight Russian troops.

Poland and Finland have indicated that they would be willing to send the tanks to Ukraine but need German approval for the move.

Asked whether Germany would allow the shipments by European allies, newly appointed Defence Minister Boris Pistorius told broadcaster ARD it would "become clear in the next few hours or tomorrow (Friday) morning".

In a separate interview with ZDF broadcaster, Pistorius added that "no one is ruling out sending Leopard tanks, or that permission or approval for the delivery by other European partners can be given".

Germany has to approve the delivery of the tanks if other countries that have bought them want to donate them to a third country.

"But until then, not all questions have been answered and that's happening currently," Pistorius said.

The defence minister, who took office earlier Thursday, however stressed that the decision would be made in coordination with Western allies, in particular the United States.

The US was "the most important and largest ally within NATO and that is why it is important that we... do this in close cooperation with the Americans", he said.

Chancellor Olaf Scholz told US congressmen in Davos that Germany will supply heavy tanks to Ukraine if the United States sends tanks too, a senior US lawmaker told AFP on Thursday.

But Washington has said that it was not prepared currently to provide advance Abrams tanks to Ukraine.

Asked if Germany would then deliver Leopard 2 tanks from its own stores without the US, Pistorius said the issue was being "discussed" by Scholz and President Joe Biden.

"I'm pretty sure we'll get a decision on that in the next few days," Pistorius said.