The sudden upsurge in fighting in eastern Ukraine has prompted the UN Security Council to call an emergency meeting on Friday, with the Minsk ceasefire accord in danger of collapse.

Army units have been on the move after some of the worst violence around the government-held town of Maryinka.

Ukraine blames pro-Russian separatists for launching an offensive to try to take the town on Wednesday, sparking a 12-hour battle.

The claims were given strong backing by international monitors from the Organisation for Security and Cooperation in Europe (OSCE) who reported movements of heavy weaponry in rebel-held areas.

“We were not able to get close to the fighting,” said OSCE spokesman Michael Bociurkiw. “The important thing that we are able to say is that there was intense fighting. The main point here is that the Minsk accords were broken, these are clear violations of the ceasefire, and not only that, violation in terms of the movement and use of heavy weaponry.”

The observers said