Russia will not be readmitted into the Group of Seven (G7) nations as US president Donald Trump has requested, German finance minister Joerg Kukies told Reuters, the latter reports.

"The condemnation of the G7 of Russia's war of aggression is very clear, especially on the third anniversary of Russia's brutal attack," Kukies said, adding that Trump's proposal would not get the unanimity required.

Kukies said the G7 could discuss longstanding proposals to use $300 billion of Russian sovereign assets frozen in Europe for the reconstruction of Ukraine, "but the discussions are just starting. It's probably a bit early to say."