The Berlin meeting today evening follows a flurry of diplomacy including a brief weekend encounter in Paris between the German, French and Ukrainian leaders.
German Chancellor Angela Merkel also has spoken by phone with Russian President Vladimir Putin and met the president of Kazakhstan, the possible host of a four-way summit on Ukraine.
Merkel and Foreign Minister Frank-Walter Steinmeier are pushing for progress on implementing a much-violated peace deal that was drawn up in September. Berlin says a substantial narrowing of differences between Ukraine and Russia is needed for a summit to take place.
The two sides have remained wide apart on major conditions of a peace deal. Ukraine and the rebels have failed to agree on a line of division, and fighting in eastern Ukraine between the government and pro-Russian rebels has escalated in recent days.
Speaking in Moscow today before heading for Berlin, Russian Foreign Minister Sergey Lavrov sternly warned Ukraine against trying to crush the pro-Russian rebellion by force.
He said that Russia expects the West to use its influence with Kiev to discourage it from launching another offensive, adding that "it will be a catastrophe."
Lavrov reaffirmed that the rebel-controlled territories should remain part of Ukraine, but stressed that the government in Kiev must implement a constitutional reform that would expand the powers of the regions.
