BERLIN

The leaders of Germany, Ukraine, Russia and France have reaffirmed their commitment to the Ukrainian cease-fire deal in a conference call, the German government spokesman has said.

The phone discussion came Thursday as fighting continued to rage in eastern Ukraine with Ukrainian government troops being forced out of the key railway hub of Debaltseve by separatists. 

Steffen Seibert said in a written statement Thursday: "German Chancellor Angela Merkel, President Hollande, President Poroshenko and President Putin have agreed to adhere to the Minsk agreements despite severe breach of ceasefire in Debaltseve.

"The leaders agree that now it is necessary to take immediate steps to fully implement the cease-fire and withdraw the heavy weapons under the monitoring of the OSCE," Seibert said, in reference to the hard-won cease-fire deal agreed after marathon talks between the leaders of Germany, Ukraine, Russia and France in Minsk on Feb. 12.

"The exchange of prisoners should also begin. For that, President Putin has agreed to use influence on the separatists," he added.  

Seibert also said that the foreign ministers of the four countries would continue discussions in the coming days on the implementation of the Minsk agreements.

More than 5,300 people have been killed and 12,200 others injured in eastern Ukraine since mid-April last year in the ongoing conflict, according to the U.N. High commissioner for human rights.