Ukraine 'build-up' raises tension

Danish Foreign Minister Martin Lidegaard (C) walks yesterday with young Ukrainian journalists, distributing their publication, 'Your choice-Freedom Ukraine', in the center of Kiev. Photo: AFP

The US and the European Union have expressed concern at reports of a build-up of separatist reinforcements in eastern Ukraine.

Shelling around the city of Donetsk on Sunday followed an intense overnight artillery bombardment, shaking an already fragile ceasefire.

Monitors and journalists reported unmarked convoys of heavy weapons, tanks and fighters close to the city.

Russia denies claims that it is supplying the separatist rebels. The EU's head of foreign policy, Federica Mogherini, said the latest reports were "worrying".

"The most recent reports by the OSCE [Organisation for Security and Co-operation in Europe] Special Monitoring Mission in Ukraine about convoys in separatist held areas with substantial amounts of heavy weapons, tanks and troops without insignia moving westwards represent a very worrying development," she said.

The White House warned that any efforts by pro-Russian rebels to seize more territory would be a "blatant violation" of the ceasefire agreement signed in Minsk.