M-55S tank of the Slovenian military. YouTube
Ukraine has repeatedly sought Leopard battle tanks from Germany to aid in its counter-attack against Russia, but Chancellor Olaf Scholz's government has so far refused.
Berlin has instead struck deals with third countries, which transfer heavy weapons to Ukraine, in exchange for receiving supplies from Germany.
In the latest such arrangement, Defence Minister Christine Lambrecht announced she had signed such an agreement with her Slovenian counterpart for Ljubljana to send 28 M-55S tanks to Ukraine.
In exchange, Germany will transfer 40 military trucks along with other supplies to Slovenia, she said in statement.
"Together, we are adding to direct arms deliveries to Ukraine to support its courageous struggle against Russian aggression," said Lambrecht.
Germany has already struck similar deals with the Czech Republic, Slovakia and Greece.
But Ukrainian Foreign Minister Dmytro Kuleba has slammed Germany's reluctance to directly send tanks, saying there was "not a single rational argument on why these weapons cannot be supplied".
Berlin has argued that it will not "go it alone" on weapons deliveries, with Lambrecht pointing out that no other ally has transferred Western-made battle tanks to Ukraine.
Scholz has been forced to repeatedly defend German's arms deliveries to Ukraine, insisting they have been substantial.