The EU's executive on Tuesday said it was eyeing the establishment of an "international prosecution office" to probe the crime of aggression in Ukraine, as a step towards putting Russia's leadership on trial.
Germany on Monday became the latest European country to throw its weight behind Kyiv's calls for a special court aimed at holding the Kremlin's top officials accountable for the war on Ukraine.
The goal is to overcome the fact that the International Criminal Court (ICC) -- which has opened an investigation into the conflict -- cannot prosecute Russia for the crime of aggression.
The European Commission floated a proposal for a specialised tribunal to target the leadership in Moscow in November, but so far there is no consensus within the bloc on its establishment.
EU justice commissioner Didier Reynders told the European Parliament that there remained "complex legal and political questions" that needed further discussion between EU states and international partners.
"Before discussions on a special tribunal could possibly gather sufficient consensus and support at the international level, an investigation mechanism could first be considered," Reynders said.
"The Commission is reflecting about the possible setting up of an international prosecution office, to start investigations into the crime of aggression, with the view to preserving and storing evidence for possible future trials."
He said discussions were going on about "legal and security issues" around the plan with the authorities in Ukraine, the ICC and the EU judicial cooperation agency Eurojust.
EU lawmakers meeting in Strasbourg are expected to back a non-binding resolution later this week calling for the establishment of the tribunal.
Ukrainian Foreign Minister Dmytro Kuleba urged them to take the step that could help ratchet up pressure on governments around the bloc to support the move.
"No impunity for Russia's political and military leadership. They must be held accountable," Kuleba tweeted.