Six people were killed in shelling in Ukraine's rebel-held city of Donetsk on Sunday, municipal authorities said on Monday, putting further strain on a 10-day ceasefire between government forces and Russian-backed separatists.
A monitoring team from the Organization for Security and Cooperation in Europe (OSCE) said it was also shelled twice in the city on Sunday despite the ceasefire, which has brought some respite in a conflict that has killed more than 3,000.
Separately, military spokesman Andriy Lysenko said in Kiev there had been some deaths among Ukrainian troops over the weekend, although he did not provide details, and said 73 soldiers had been freed in an exchange with the rebels.
The truce started on Sept. 5 and has been broadly holding despite sporadic violations which both sides blame on the other.
On Saturday there was particularly heavy fighting around Donetsk airport, which remains under government control.
The rebels' main leader in Donetsk on Monday accused Ukrainian forces of violating the truce repeatedly and suggested it could not hold much longer.
"I do not see the sense in (further) consultations. There have to be measures which must first be undertaken and then consultations can take place," Alexander Zakharchenko told reporters in Donetsk.