BERLIN: German Chancellor Olaf Scholz said on Saturday that a Russian attack on Ukraine would be a "serious mistake" with high "political, economic and geostrategic costs".

There was no justification for some 100,000 soldiers massing on Ukraine's borders, he told the Munich Security Conference in a livestreamed speech.

"Russia has made the issue of Ukraine's possible NATO membership a casus belli, which is a paradox because here is no decision on this on the agenda," he said.

US says 40% of Russian forces on Ukraine border in attack position

The West was nonetheless ready to negotiate over Russia's security demands "without being naive".

"We will differentiate clearly between untenable demands and legitimate security interests," he added.