A destroyed Ukrainian army tank is seen near the village of Lebedynske, on the highway joining Mariupol and Novoazovsk, Ukraine, Saturday, Sept. 6, 2014. After four months of war, eastern Ukraine begins the first full day of an uncertain cease-fire. The truce agreement calls for an exchange of prisoners and establishment of humanitarian corridors, but how quickly those actions will begin is unclear.

Image Credit: AP Photo/Sergei Grits

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.

A statement from Ukrainian President Petro Poroshenko's appeared to make glancing reference to the cease-fire's tentativeness, saying said he and Russian President Vladimir Putin discussed steps "for giving the cease-fire a stable character" in a telephone conversation Saturday.

But, it said, both leaders assessed the cease-fire as having been "fulfilled as a whole."

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 that the cease-fire had been violated with two rounds of shelling in the town of Amvrosiivka, about 50 kilometers (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.

A burned Ukrainian army tank is seen near a destroyed kindergarten in the village of Kominternove, Ukraine, Saturday, Sept. 6, 2014.

Image Credit: AP Photo/Sergei Grits

Ukraine had received information that the rebels on Friday "were preparing a press conference for today (in which) one of the points was the condemnation of the Ukrainian military for violation of the cease-fire," Lysenko said through a translator. "So we do not exclude that they tried to provoke the Ukrainian military to fire."

Earlier Saturday, the mayor's office in Donetsk said there had been no reports of shooting or shelling there although some shelling had been heard late Friday afternoon. The city council of the second-largest rebel-held city of Luhansk, which had endured intense fighting for weeks, also reported the night was quiet.

Ukraine, Russia and the Kremlin-backed separatists signed the cease-fire deal Friday in Minsk, the Belarusian capital, in an effort to end more than four months of fighting in the region. The negotiators also agreed on the withdrawal of all heavy weaponry, the release of all prisoners and the delivery of humanitarian aid to devastated cities in eastern Ukraine.

If the ceasefire holds, it would be a landmark achievement for both sides. Fighting between pro-Russian rebels and Ukrainian government troops has ravaged the already teetering Ukrainian economy, claimed at least 2,600 civilian lives and left hundreds of thousands homeless, according to United Nations estimates.

An abandoned Ukrainian army tank is seen in the village of Kominternove , Ukraine, Saturday, Sept. 6, 2014.

Image Credit: AP Photo/Sergei Grits

But Western leaders voiced skepticism over Russia's commitment to the deal. A previous 10-day cease-fire, which each side repeatedly accused the other of violating, yielded few results at the negotiating table.

U.S. President Barack Obama said he was hopeful the cease-fire would hold but unsure the rebels would follow through and that Russia would stop violating Ukraine's sovereignty and territorial integrity.

"It has to be tested," Obama said Friday at the closing of a two-day NATO summit in Wales.

Both the U.S. and the European Union have prepared even tougher sanctions on Moscow, and Obama stressed that the most effective way to ensure the cease-fire's success was to move ahead with those measures and maintain pressure on Russia. According to an EU diplomat, these new measures would target Russia's access to capital markets and trade in arms and defense technology, dual-use goods and sensitive technologies. The new sanctions were given preliminary approval Friday night and could be implemented as early as Tuesday.

"If certain processes get underway, we are prepared to suspend sanctions" against Russia, German Chancellor Angela Merkel said.

Ukraine, NATO and Western nations have accused Russia of backing the separatists with weapons, supplies and thousands of regular troops. Moscow has denied this, but a NATO military told The Associated Press that the number of Russian soldiers directly involved in the conflict has grown past the alliance's earlier estimate of at least 1,000.

In a statement published online Saturday, Russia's foreign ministry condemned further EU sanctions and promised that "there will undoubtedly be a reaction from our side" to any new measures. In August, Russia passed a sweeping ban on meat, fruit, vegetables, and dairy product imports from the EU, the U.S. and a host of other countries who imposed sanctions on Russia.

News from © The Associated Press, 2014