PARIS, June 29 (Reuters) - The leaders of France and Germany spoke for more than two hours by telephone on Sunday with Russia's Vladimir Putin and Ukraine's Petro Poroshenko, seeking progress before a Ukraine ceasefire expires, the French president's office said.
Francois Hollande and German Chancellor Angela Merkel "stressed the importance of further concrete progress towards the stabilisation of security on the ground, the extension of the ceasefire and the implementation of the peace plan presented by the Ukrainian authorities," Hollande's office said in a statement.
Ukraine extended its truce by 72 hours until Monday night, coinciding with a deadline set by European Union leaders on Friday for pro-Russian rebels to agree ceasefire verification arrangements, return border checkpoints to Kiev authorities, free hostages and launch serious talks on implementing Poroshenko's peace plan.
The separatist rebels in eastern Ukraine on Saturday released a second group of four monitors from the Organization for Security and Cooperation in Europe (OSCE) who had been seized on May 29, a Reuters witness said.
But the ceasefire appeared under threat when three members of the Ukrainian military were killed in a rebel attack on their post near the eastern city of Slaviansk. (Reporting by Sybille de La Hamaide; Editing by Ruth Pitchford)