French President Francois Hollande, German Chancellor Angela Merkel, Russian President Vladimir Putin and Ukrainian President Petro Poroshenko held phone talks late on Monday, the French presidential office, the Elysee, said in a press release.
The four leaders reaffirmed their commitment "to do everything for the full implementation of the Minsk accord as quickly as possible."
Members of the Normandy Format -- senior diplomats from the four countries working to resolve the situation in eastern Ukraine -- stressed in the phone talks the importance of putting in place all necessary measures to consolidate the ceasefire agreement in eastern Ukraine, beginning with withdrawing heavy weapons and releasing prisoners.
The 13-point Minsk agreement, outlining the steps needed to end the conflict, was reached in February 2015 in talks involving leaders of Ukraine, Russia, Germany and France.
The main provisions of the deal include a comprehensive ceasefire, withdrawal of heavy weapons from the frontline of fighting, release of captives, amnesty to detained insurgents and restoration of the Ukrainian government control over the state border.