Kiev forces and independence militias must respect the ceasefire in the whole conflict zone, including Debaltsevo, the leaders of Ukraine, France, Germany and Russia agreed in a phone conversation, the Ukrainian president 's official website said on Sunday.

Ukrainian President Petro Poroshenko held a telephone conversation with German Chancellor Angela Merkel, French President Francois Hollande and Vladimir Putin of Russia.Their joint position is that cease-fire should apply to the entire front line, including the area around Debaltseve.

"Joint stance of the 'Normandy Format' is that the ceasefire must apply on the whole line of contact, including formations in the area of Debaltsevo," the statement said.

The leaders of Russia, Ukraine, France, and Germany have agreed to continue talks on February 16, according to the Ukrainian president’s website.

Several thousands of Ukrainian troops currently remain encircled in the key town of Debaltsevo in the Donetsk region.

The Normandy Quartet noted the necessity of establishing the proper conditions for the Organization for Security and Co-operation in Europe observers in Donbas.

The truce deal between the Ukrainian troops and pro-independence forces in Donbas was brokered by the Normandy Quartet. The document was signed on Thursday, in Minsk.

Apart from the ceasefire, Kiev and independence militias must exchange all prisoners and establish a buffer zone in the conflict area.

A similar agreement was signed last September. However, the clashes in eastern Ukraine continued and even intensified in the first weeks of 2015.