As deadly clashes raged between protesters and police, the envoys from Germany, France and Poland then took the plan to opposition leaders and said they would stay in Kiev for more talks tomorrow.
They had been due to return to Brussels today for a meeting to discuss sanctions against the Ukrainian government over the bloody escalation in the three-months-old standoff.
In over four hours of talks in Kiev, the foreign ministers and embattled Yanukovych discussed "ideas for a roadmap" toward a peaceful solution, the German delegation source said.
A French diplomatic source said the three ministers had gone to Kiev with "some ideas" - including to try to "bring a halt" to the violence, start real negotiations, revise the constitution in a more democratic direction and hold early elections.
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On this basis, "a form of mediation is taking place," added the source.
Polish Foreign Minister Radoslaw Sikorski earlier said on Twitter that the three would also hold talks with the opposition "so as to test proposed agreement", without elaborating.
In a last-minute change of plan, the ministers -- France's Laurent Fabius, Germany's Frank-Walter Steinmeier and Poland's Sikorski -- stayed on in Kiev rather than fly to Brussels to join their EU colleagues.