A Ukrainian soldier has been killed and several others wounded as heavy fighting erupted in eastern Ukraine, the country's military said. Ukraine and Russian-backed separatists blamed each other for the flare-up.

The violence is some of the worst since a Paris summit in December tried to narrow positions between Kyiv and the separatists on implementing a peace deal, and it comes before a possible second summit on the same issue in Berlin.

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Ukraine's military said in a statement on Tuesday that the separatists attempted to advance into the Kyiv-controlled territory but were repelled. They also accused the separatists of using heavy shelling to try to breach Ukrainian lines.

Colonel-General Ruslan Khomchak, the chief of the general staff of Ukraine's armed forces, said one Ukrainian soldier was killed and five others were wounded. He said four separatists were also killed, while six of them were injured.

Separatist authorities in the Luhansk region, however, blamed Ukraine for starting the fighting, saying a small group of soldiers had tried and failed to break through their lines.

They said the group had stumbled into a minefield which had left two Ukrainian soldiers dead and three others injured. Ukrainian forces then shelled civilian areas, they added.

'Cynical provocation'

Ukrainian President Volodymyr Zelenskyy said in a statement the attack was an attempt to derail efforts at the peace process.

"This is not just a cynical provocation ... it is an attempt to disrupt the peace process in the Donbass, which had begun to move through small but continuous steps," Zelenskyy said.

He later said he did not believe the fighting would stymie efforts to end the conflict, in which more than 13,000 people have been killed since 2014 despite a 2015 ceasefire deal.

Zelenskyy also said he would call a meeting of his Security Council to discuss the situation.

"Our course for ending the war and our adherence to international agreements remain unchanged, just as our determination to repel any acts of aggression against Ukraine," he said.

Al Jazeera's Step Vaessen, reporting from Moscow, said the attack occurred in the early morning at a crucial location near a demilitarised zone, describing it as the heaviest fighting to take place since the peace process was renewed after Zelenskyy took office in May last year.

"He promised to bring peace to eastern Ukraine; it was one of his biggest election promises," Vaessen said.

"Then he started a process where prisoners were exchanged, there was a demilitarisation process going on [and] troops were withdrawn."

Russia not involved: Kremlin

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The Kremlin said it had seen reports of the clashes and was looking into them. It said it did not know what had triggered the violence.

On Tuesday Russian President Vladimir Putin dismissed Vladislav Surkov, a veteran and once close adviser who until recently managed Moscow's relations with war-torn Ukraine.

Putin fired Surkov, seen as a hardliner by many in Kiev, a week after the Kremlin said senior Ukrainian-born Russian official Dmitry Kozak was now in charge.

Ukraine, Western countries and the NATO accuse Russia of sending troops and heavy weapons to prop up separatist fighters in Donbass, a charge that Moscow has denied.

A 2015 peace deal brokered by France and Germany helped reduce the scope of fighting, but sporadic clashes have continued and efforts to negotiate a political settlement have stalled.

During a meeting in Paris in December, the leaders of Russia, Ukraine, France and Germany made a deal to exchange prisoners and pledged to ensure a lasting ceasefire in fighting between Ukrainian troops and Russia-backed separatists.

They made no progress, however, on key contentious issues - a timeline for local elections in eastern Ukraine and when the country can get back control of its borders in the rebel-held region.