Two Ukrainian servicemen killed in past 24 hours - Ukraine military
Separatist officials said there had been no significant attacks on rebel-held territory by Ukrainian forces over the weekend, separatist press service DAN reported.
Both sides accuse the other of regularly violating a ceasefire deal signed in Minsk in February, but a surge in violence in the past few weeks has caused international monitors to warn of a threat of a wider escalation.
"Around Donetsk, particularly near the airport, there is military action practically round-the-clock ... The enemy has pulled banned weapons into Donetsk - tanks and high-calibre guns - and is actively using them," military spokesman Andriy Lysenko said.
"The growing number of attacks shows that rebels have focussed on this area in order to advance," he said at a briefing in which he gave casualty figures in the 24 hours up to 6 a.m.
The situation near the strategic Kiev-controlled port city of Mariupol in south-east Ukraine was also "extremely tense" on Sunday with rebels using artillery and sniper fire to attack government positions, Lysenko said.
(Reporting by Natlalia Zinets; Writing by Alessandra Prentice; Editing by Richard Balmforth)