The rebel stronghold of Donetsk on 23 February joined Russia in celebrating a nationwide holiday, the Defender of the Fatherland Day.
Red flags with the hammer and sickle were visible over Lenin Square in the city centre, as locals gathered to celebrate the Soviet-era holiday, that is not marked in Ukraine.
Men in military uniforms filled the square where rebel officials took to a podium and praised the achievements of rebel military units.
Ukraine's military announced it could not start withdrawing heavy weapons from the front line in the east, as required under a tenuous ceasefire, because pro-Russian separatists who advanced last week were still attacking its positions.
Kiev on Monday accused pro-Russian rebels of opening fire with rockets and artillery at villages in south-eastern Ukraine on Monday, all but burying a week-old European-brokered ceasefire deal.
The reported shooting came closer to killing off the truce, intended to end fighting that has killed more than 5,600 people, which rebels ignored last week to capture the strategic town of Debaltseve in a punishing defeat for Kiev.
Kiev and its Western allies say they fear the rebels, backed by reinforcements of Russian troops, are planning to advance deeper into territory the Kremlin calls "New Russia". Moscow denies aiding the rebels.