Ukraine President Volodymyr Zelenskiy is holding a security council meeting on Tuesday after a soldier was killed and four more injured in what Kyiv said was heavy shelling by pro-Russian forces in the eastern Donbass region.

The violence is some of the worst since a Paris summit in December, where parties tried to implement a peace deal between the fighting factions. Another summit is expected to be held soon in Berlin.

"This is not just a cynical provocation," said Zelenskiy, in response to the flare-up: "It is an attempt to disrupt the peace process in the Donbass, which had begun to move through small but continuous steps."

He added that the fighting would not stop efforts to resolve the conflict, in which more than 13,000 people have died since 2014, despite a 2015 ceasefire deal.

On announcing the death of one of its soldiers, Ukraine's army also accused pro-Russian forces of using heavy shelling to try to break through government lines.

But the separatists said that Kyiv had attacked first, stating that a group of Ukrainian soldiers had tried to break through their lines, but had stumbled into a minefield, with two fighters losing their lives.

Ukrainian government forces had then shelled civilian areas, they added. The Kremlin said it was following reports of the clashes and was investigating.

Ukraine and NATO have accused Russia of sending troops and heavy weapons to back separatist fighters in Donbass, which Moscow denies.

Zelenskiy was elected last year on the promise of bringing an end to the conflict. He has had some success since the beginning of his tenure, with Ukraine and Russia implementing confidence-building policies, including prisoner swaps and planned troop withdrawals in certain areas.