Ukrainian soldier leaves a trench at a check point on a road in the eastern Ukrainian city Mariupol, Ukraine, on Sunday.

DONETSK : Heavy fighting erupted around the rebel stronghold of Donetsk in eastern Ukraine on Sunday, piling further pressure on a precarious nine-day-old truce between the government and separatist fighters.

Large clouds of thick black smoke billowed over the industrial city as the boom of sustained shelling and the rattle of automatic gunfire rang out, reporters witnessed.

Kiev accused the rebels of jeopardizing the truce by intensifying attacks on government positions in eastern Ukraine, the scene of five months of deadly combat.

Sunday’s fighting appeared to be concentrated near Donetsk airport where the Ukrainian military said it had driven back a major assault by insurgent fighters on Friday.

“The terrorist actions are threatening the realization of the Ukrainian president’s peace plan,” said National Security and Defense Council spokesman Volodymyr Polyovy.

He also took aim at comments by two rebel leaders who both signed the 12-point truce deal in Minsk on September 5, but who declared on Sunday they were mere “observers” at the talks.

The cease-fire deal has largely calmed a conflict that has cost more than 2,700 lives and set off the worst crisis in East-West relations since the Cold War.

Rebels and government forces have since swapped dozens of captives under the accord, and Ukrainian President Petro Poroshenko has pledged to offer the eastern regions that form the economic backbone of Ukraine some limited self-rule.

But the insurgents on Sunday accused Kiev’s forces of firing at them.

“From our side, nobody is shooting but they are breaking the rules, everybody in the world knows it,” said a rebel commander defending a checkpoint near the village of Olenivka south of Donetsk.

The simmering crisis has exposed layers of mistrust between both the West and Moscow and between the largely Russian-speaking populations in the east of Ukraine and the pro-Western leaders in Kiev.

Ukrainian Prime Minister Arseniy Yatsenyuk accused Russian President Vladimir Putin on Saturday of keeping Ukraine in a state of war to create a “frozen conflict” in Russia’s backyard.

“He wants to eliminate Ukraine as an independent country,” Yatsenyuk said.

The West has been acting to isolate Putin, who is seen as less predictable and more aggressive than at any point since his domination of Russia began 15 years ago, and in turn pledged greater support for the government in Kiev.

 
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