German Chancellor Friedrich Merz said he had made clear to U.S. President Donald Trump in a long phone call on Friday evening that Europe needs to be a part of any process to end Russia's war in Ukraine.

Wars cannot be ended by major powers over the heads of the countries affected, said Merz, adding that the war can only be ended with the consent of Ukraine and of Europe.

"If Ukraine loses this war and possibly collapses, it will have an impact on European politics as a whole, on the entire European continent. And that is why we are so committed to this issue," Merz said after the G20 summit in Johannesburg.

"There is currently an opportunity to end this war, but we are still quite a long way from a good outcome for everyone," he added. Merz said he also reminded Trump of how Russia dealt with the Budapest Memorandum, a 1994 deal in which Kyiv gave up its nuclear arsenal in exchange for security assurances that proved insufficient to deter Russia.

"That is why other security guarantees must now be given, other more reliable agreements must be made," he added.