KIEV, Ukraine — After more than four months of bloodshed, a cease-fire in Ukraine’s rebellious east largely held back fighting Saturday but appeared fragile as both sides of the conflict claimed the others had violated the agreement.

Col. Andriy Lysenko, a spokesman for Ukraine’s national security council, told reporters that rebels had fired at Ukrainian forces on 10 occasions after the cease-fire was to take effect, but all the incidents he detailed were on Friday night.

In Donetsk, the largest city controlled by the Russian-backed separatists, the night passed quietly — a rarity after several months of daily shelling in residential areas. But Alexander Zakharchenko, the top separatist leader from Donetsk, told the Russian news agency RIA Novosti the cease-fire had been violated with two rounds of shelling in the town of Amvrosiivka, 30 miles southeast of Donetsk.

“At this time the cease-fire agreement is not being fully observed,” he said. He didn’t say when the supposed breach was to have occurred.

Lysenko said Ukrainian forces were strictly observing the cease-fire and suggested that Zakharchenko’s claim was a provocation.