"My diplomatic year will start on January 15 in Astana (Kazakhstan) with Normandy-style talks," Poroshenko said in reference to crisis negotiations between the four leaders that were first held in June in France.
Poroshenko's announcement came after his envoy resumed direct negotiations with the insurgents last week in the Belarussian capital Minsk.
But those talks quickly broke down due to differences over how to achieve a lasting ceasefire and mutual withdrawal of forces from the front line in the former Soviet republic's Russian-speaking industrial east.
Merkel urged Putin at the weekend to put more pressure on separatist leaders to sign a comprehensive peace deal that Poroshenko had hoped to reach last week to end the eight-month uprising.
Putin denies US and EU charges of backing the guerrillas in retribution for the February ouster in Kiev of a Moscow-backed president and subsequent rise to power of a pro-European team.