KIEV, Ukraine (AP) -- Ukrainian officials say Russia-backed separatists violated a troubled cease-fire a dozen times during the night with artillery and rocket attacks and an attempt to storm a Ukrainian encampment.
Explosions were heard in the main rebel-held city Donetsk around dawn on Sunday and a rebel website says several buildings in the city were damaged by artillery.
Despite the reported violations, the level of firing appeared to be far lower than a week ago when a cease-fire was called.
Among the attacks reported by the Ukrainian military was an attempt to storm positions in the village of Shyrokyne near the port city of Mariupol. That city remains of strategic concern to Ukraine because rebel seizure of it could help establish a land corridor between mainland Russia and the Russia-annexed Crimean peninsula.