A Downing Street spokesperson said:
The Prime Minister called President Poroshenko this afternoon to discuss the situation in eastern Ukraine.
Both leaders expressed concern about the situation on the ground. While the level of fighting has lessened considerably since the ceasefire came into force at midnight, there have been multiple violations in particular around the town of Debaltseve. They agreed on the importance of both sides respecting the ceasefire.
They discussed what role the United Nations Security Council could play in supporting the ceasefire and the agreements reached in Minsk in September 2014 and February 2015, and agreed on the importance of underlining Ukraine’s territorial integrity.
They agreed to stay in close touch in the coming days.