Ukraine's cease-fire appeared to be under pressure just over a day after it was declared as shelling was reported near the southeastern city of Mariupol, reports GHN based on Fox News.
The port has been the focus of an offensive by pro-Russian separatists in recent days that has reversed the gains of Ukrainian government forces, who had encircled the major rebel-held strongholds of Donetsk and Luhansk.
Reporters from the BBC and Reuters reported hearing explosions in the eastern part of the city early Sunday. The Reuters reporter said he saw a truck, a gas station, and an industrial facility on fire within the city limits. The reporter also saw trucks carrying pro-Kiev militia volunteers, as well as tanks and armored personnel carriers racing in the direction of the eastern part of the city.
A Ukrainian officer told the news agency, "There has been an artillery attack. We received a number of impacts. We have no information about casualties."
The Washington Post reported that Ukraine's Interior Minister, Arsen Avakov, had accused Russia of violating the cease-fire, saying the rockets had been fired at Ukrainian positions 16 times from Russian territory.
"Are you surprised that [Vladimir] Putin is treacherous?" Avakov reportedly wrote in a statement on his Facebook page, referring to Russia's president. "This has not canceled our determination to defend Mariupol."
Earlier Saturday, the presidents of Ukraine and Russia said the cease-fire was mostly holding, but the truce still appeared fragile as both sides of the conflict claimed violations.
A statement from Ukrainian President Petro Poroshenko's office 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." A separate Kremlin statement about the call said, "There was a mutual satisfaction with the fact that the sides of the conflict were overall observing the cease-fire regime."