"There must be no failure because the situation in eastern Ukraine is becoming more threatening," Steinmeier said ahead of Thursday's Geneva meeting between top diplomats of the EU, US, Russia and Ukraine.
Earlier on Wednesday Russian President Vladimir Putin warned Chancellor Angela Merkel that Ukraine was on the verge of civil war after the Kiev government sent in the army against separatists in the east of the country.
"The Russian president remarked that the sharp escalation of the conflict has placed the country, in effect, on the verge of civil war," the Kremlin said in a statement on telephone talks between the two leaders.
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