Ukrainian President Petro Poroshenko has held a telephone conversation with British Prime Minister David Cameron, the presidential press service has reported.
The parties discussed the situation in Donbas after the announcement of the ceasefire at midnight on February 15.
Poroshenko said that observance of permanent and comprehensive ceasefire throughout the contact line is necessary for further withdrawal of heavy weapons.
Cameron, in his turn, assured Poroshenko that the UK will continue its policy of ensuring unity in the European Union on sanctions against Russia if the parties fail to implement the terms of the Minsk agreements.
He also noted that Ukraine could count on the support of Britain as a permanent member of the UN Security Council.
The parties also agreed on their close coordination of further steps to achieve a peaceful resolution of the conflict in Donbas.