Paris - Russian President Vladimir Putin and his Ukrainian counterpart, Volodymyr Zelensky, agreed on a full ceasefire in eastern Ukraine by the end of the year as they met for the first time on Monday.

But Zelensky, who has said resolving the conflict is his top priority and has reached out to Putin since being elected in April, warned that "real facts" were needed and noted that multiple previous ceasefires with pro-Russian rebels had failed.

The talks were brokered by German Chancellor Angela Merkel and French President Emmanuel Macron, who has also committed political capital to improved relations with Russia. The four leaders said they also wanted a full release of prisoners in the conflict by the end of the year. But they admitted that progress on political issues to bring the five-year conflict to a close was more complicated.

Putin and Zelensky remained firm in their positions about when elections should be held in the Donbass region - before Ukraine regains control of the border with Russia, or, as Zelensky insists, once it has done so.

A potential agreement to resolve the conflict 

Putin and Zelensky shook hands before the summit meeting and worked on a potential agreement towards resolving the conflict, Russian state media quoted the Kremlin as saying.

Zelensky has reached out to Putin since his election in April and recent months have seen several confidence-building steps including troop pullbacks and exchanges of prisoners.

Ahead of the talks, German Foreign Minister Heiko Maas said the European Union was still likely this week to renew sanctions imposed on Russia for its role in the eastern Ukraine crisis.

"So far I see no reason to change anything about this decision," Maas said in Brussels ahead of a meeting with EU counterparts. Resolving the crisis would be a "precondition for the relationship between the EU and Russia to improve," he added.

Putin represents the Rebels

The rebellion in eastern Ukraine erupted after Kiev's pro-Russian president was ousted in a 2014 political pivot towards the West and away from Russia's traditional sphere of influence. While Putin represents the Donbass separatists in international peace talks, his government has repeatedly denied allegations of direct involvement in the conflict. Ukraine accuses Russia of waging war on its territory.

A map shows the part of Ukraine controlled by a pro-Russian separatist.

About 13,000 people have been killed in the conflict, according to estimates by the United Nations. Several hundred people protested outside Zelensky's office in Kiev on Monday, demanding that Zelensky not compromise with Putin to give up territory in the war-torn regions.

Separate to the summit, Russia announced that it had given citizenship to 125,000 people from rebel-held parts of eastern Ukraine this year, under a law signed by Putin. The most likely outcome is for the conflict to become frozen, like in Transnistria, a disputed Moldovan region that maintains a Russian peacekeeping force, according to Ukraine conflict expert Taras Zahorodniy.

Achieving peace depends on Russia

Progress in achieving peace in the Donbass "depends not on Ukraine, but on Russia," said Zahorodniy, director of the National Anti-Crisis Group, a political and conflict assessment think tank based in Kiev.

"There is a window of opportunity connected with Russia's desire to get sanctions removed, the EU's desire to remove the sanctions, and Zelensky as a neutral figure with whom it's possible to negotiate to enable Russia to leave the Donbass and save face," Zahorodniy told dpa.

Regional expert Diyar Autal agreed that a potential resolution of the conflict would be up to Russia - but that they may still try to keep control of the Donbass. "The primary obstacle to the settlement of the conflict is Moscow's unwillingness to relinquish control over the breakaway territories," said Autal, an associate of Harvard University's Davis Center for Russian and Eurasian Studies.

Control over the conflict areas enables Russia to assure that Ukraine will not join the Western military alliance NATO, Autal told dpa. The conflict essentially "provides Putin with a veto power over Ukraine's potential NATO membership," Autal said.