As diplomats scrambled to finalise a deal to end the 10-month war, pro-Russia rebels sought to encircle railway hub Debaltseve and Ukrainian forces launched a counter-offensive around the strategic port of Mariupol.
Ukrainian President Petro Poroshenko said rockets for the first time hit the military's command centre in Kramatorsk, the government's administrative capital in the region, well behind the frontlines and far from rebel positions.
The strikes also hit residential areas around the city, killing 15 local residents, officials said. At least 63 people, including five children, were also wounded. Kiev and the West accuse Moscow of supplying and training the heavily armed separatists, but Russia denies the claims.
Rebels say their weapons have been captured from Ukrainian forces, although Kiev has cited numerous cases of the insurgents using advanced weapons that are only available from Russian arsenals.
Poroshenko said rockets for the first time hit the military's command centre
"The shelling is with Vladimir Putin's compliments, who else could have done this?" shouted a Kramatorsk resident as he walked past an unexploded rocket. Another seven Ukrainian soldiers and eight civilians were killed in fighting over the last 24 hours, Kiev officials and rebels said, including in Debaltseve, which the insurgents claim to have surrounded.
Rebels, who rarely give a military toll, said that seven of their fighters had been killed. Ukrainian forces took control of three villages east of Mariupol, around 90 kilometres south of the rebel stronghold Donetsk, and fierce fighting raged for control of two more, senior interior ministry advisor Zoryan Shkiryak said.