Talks to assess the implementation of a cease-fire in eastern Ukraine have begun in Berlin.
The meeting brings together German Foreign Minister Frank-Walter Steinmeier, French Foreign Minister Laurent Fabius, Russian Foreign Minister Sergei Lavrov, and Ukrainian Foreign Minister Pavlo Klimkin.
The conflict between Russian-backed rebels and government troops in eastern Ukraine has killed more than 6,000 people since April 2014
The cease-fire agreement brokered by the German and French leaders in the Belarusian capital of Minsk in February has reduced hostilities, but violations are reported regularly.
Under the truce, fighting was supposed to stop and heavy weapons were to be pulled back from the front line.
Ahead of the Berlin talks, Steinmeier urged Moscow and Kyiv to move ahead with implementation of the Minsk deal, which also set out steps to regulate relations between Kyiv and rebel-held parts of the Donetsk and Luhansk provinces and to help them recover from a year of fighting.
"My colleagues and I will discuss how a political process could be started. We also plan to discuss the formation of working groups," Steinmeier told reporters.
He said the Minsk agreements "were devoted not only to the cease-fire, but to something more significant, as they are about the launching of a political process, which would eventually, as we hope, result in a political settlement of the conflict."
Responsibility for verifying the cease-fire lies with monitors from the Organization for Security and Cooperation in Europe (OSCE).
Fabius, speaking on the sidelines of an EU foreign ministers meeting in Barcelona, Spain, said he was concerned by the "number of violations of the cease-fire."
"We are going to remind our colleagues -- both Russian and Ukrainian -- that the Minsk process must be respected and must be respected before the end of the year, since that's the cutoff," he said.
A preparatory meeting of experts was held earlier on April 13 ahead of the Berlin talks.
Progress, But 'Not Enough'
Prospects for a settlement are clouded by disputes over those aspects of the deal.
"We expect both Moscow and Kyiv to seize the central issue of the implementation of the next phase of Minsk," Steinmeier said in an interview with the Die Welt newspaper.
The next phase foresees "the preparation of local elections in the areas occupied by the separatists, but also humanitarian access and reconstruction in eastern Ukraine," Steinmeier said.
Steinmeier said OSCE observers were making progress, "but it is not enough."
He also point to the "well advanced withdrawal of heavy weapons."
Steinmeier's largely upbeat assessment was echoed recently by French Foreign Minister Laurent Fabius who said on April 9 that "some progress" has been achieved on the ground despite cease-fire violations.
However, an unnamed NATO official told another newspaper, the Frankfurter Allgemeine Zeitung, on April 12 that Russia was still supplying troops and weapons to the separatists in Ukraine, in violation of the Minsk accords.
"We have noticed again support for the separatists, with weapons, troops and training. Russia is still sending troops and arms from one side of the open border with Ukraine to the other," the Germany daily quoted the official as saying.
On April 10, the Ukrainian military accused the rebels of intensifying attacks, especially around the airport in the rebel-held city of Donetsk.
The military said the rebels were using heavy weapons, which are supposed to have been withdrawn from the front line.