Top leaders of Russia, Germany and Ukraine have agreed on the monitor mission of the Organization for Security and Cooperation in Europe (OSCE) in eastern Ukraine, said the Kremlin on Tuesday.

"The leaders exchanged views on the role of the OSCE in current phase of the monitor mission," said the Kremlin press service in a statement posted on its website.

Discussions were conducted on the implementation of the package of measures agreed at the quartet negotiation in Belarus' capital of Minsk last week, in particular on concrete steps of the ceasefire, the withdrawal of heavy weapons and situation in the eastern Ukrainian town of Debaltsevo, said the statement.

Debaltsevo, a small railway hub lying between the two rebel strongholds of Donetsk and Lugansk, has become one of the main flashpoints in recent weeks, as some 8,000 Ukrainian troops have reportedly been encircled by militia in Debaltsevo, a claim denied by Kiev.

The OSCE on Monday released an online daily report on the situation in Ukraine, confirming that the conflicting sides in Ukraine generally observed the ceasefire in the first 18 hours, despite some firing incidents in several locations in eastern Ukraine including Debaltsevo, Sievierodonetsk, Lugansk and Donetsk.

Russian President Vladimir Putin, German Chancellor Angela Merkel and Ukrainian President Petro Poroshenko also agreed to continue contacts in different formats in order to facilitate the implementation of the Minsk agreements.

Local media reported that an online video conference of the Contact Group would be held Tuesday to discuss a number of "day-to-day issues."

Putin, Merkel, Poroshenko and French President Francois Hollande struck the ceasefire deal in Minsk on Thursday in a bid to end the violence in Ukraine's eastern regions of Donetsk and Lugansk.

The OSCE is to serve as a mediator and observer of the implementation of the Minsk agreements reached by the Ukrainian conflicting sides.