The leaders of Ukraine, Germany and Russia, Petro Poroshenko, Angela Merkel and Vladimir Putin, have agreed over the phone on specific steps to ensure the OSCE observers can monitor the ceasefire in eastern Ukraine, according to a communiqué issued by the German government on Tuesday.

"In connection with the situation in Debaltseve, where starting from February 15 a comprehensive ceasefire has not been established, the parties agreed on specific steps that will enable the OSCE to monitor the situation in the area," the German government said.

The communiqué also said that the German chancellor and the Ukrainian president had urged the Russian president to use his influence over the separatists to stop the shelling.

The German government also recalled that according to the Minsk agreements, the withdrawal of heavy weapons should start on Tuesday.

The Ukrainian president's press service reported that during the conversation, Poroshenko urged Putin to take every step possible to facilitate a full and unconditional ceasefire, especially in the area of Debaltseve, and to start the withdrawal of heavy weapons under the OSCE monitors' control.