Nato member Poland said on Wednesday it wanted to send Leopard battle tanks to Ukraine, raising pressure on Germany to approve the transfer.
On a visit to Ukraine, Polish President Andrzej Duda said the German-made tanks would be offered “as part of building an international coalition”.
There was no indication that Germany, which claims the final say on how weapons from its factories are used, had agreed to such a move.
Pressure has been mounting on German Chancellor Olaf Scholz to allow the Leopards to be donated, or to provide them from Germany's own stocks, to help Ukraine regain territory from Russia.
“The war is not ending,” Mr Duda said. “Everything indicates that Russia will continue to wage a war of attrition against Ukraine.”
Ukraine is seeking donations from several allies because no one country will be able to supply enough, President Volodymyr Zelenskyy said at a briefing with Mr Duda on Wednesday.
At the meeting in Lviv, western Ukraine, Mr Duda and Lithuanian President Gitanas Nauseda agreed to “continue providing powerful military, technical, defence, humanitarian and other support”, Mr Zelenskyy's office said.
Germany last year offered Leopards to the Czech Republic to replace Soviet-era equipment being sent to Ukraine.
But there were no known western tank donations until France this month announced it would send some light vehicles.
Germany then announced it would donate Marder fighting vehicles, but Ukraine has for months been asking for the heavier Leopards, a model first used by West German forces during the Cold War,
“I think that the German government also understands somewhere deep in its soul that this decision will be approved and the tanks will be given to Ukraine,” Ukrainian Foreign Minister Dmytro Kuleba said on Tuesday.
Visiting Mr Kuleba in Ukraine, German Foreign Minister Annalena Baerbock said Berlin would send more weapons, without specifying which ones.
Ukraine conflict - in pictures
Mr Scholz's spokesman said on Wednesday that he was not aware of any formal requests for the transfer of Leopards to Ukraine.
Any such requests would be examined as and when they are made, he said.
Berlin has previously endorsed the shipment of German-made howitzers from the Netherlands, and of Czech and Estonian stocks that once belonged to communist East Germany.
It has justified its caution on tank shipments by saying it will not act unilaterally or risk making Nato a party to the conflict.
Top defence officials from the US, Britain, Germany and other Nato allies will hold their next round of talks at a US base in Germany on January 20.
