KIEV (Reuters) - 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.
"There is no ceasefire. There is no exchange of prisoners ...," he said.
Government forces last month had been tightening their grip on Donetsk, a major industrial hub with a pre-war population of about one million. But they then suffered serious losses east of the city and in the south-east, with Kiev accusing Russia of directly intervening to support the rebels.
Russia denies charges that it has sent troops into Ukraine and that it has also been arming the rebels.
The ceasefire deal was negotiated by envoys from Ukraine, Russia, the separatists and the OSCE.
Donetsk city council said two northern districts of the city were shelled on Sunday, damaging homes and public buildings. "As a result of the shelling, six civilians were killed and 15 people were wounded by shrapnel to varying degrees," it said.
An OSCE statement said four shells had exploded about 200 meters (655 feet) from a monitoring team which had driven in marked vehicles to a Donetsk market place where there had been earlier reports of shelling.
After the team moved to a new location, another mortar shell exploded nearby and the team pulled out of the area.
None of the OSCE team was injured, though the statement said the monitors had seen the body of a woman lying in the street.
"All six colleagues were able to get back to base, but both vehicles were badly damaged," spokesman Michael Bociurkiw said. "We regard this as a very serious incident. It's the first time our vehicles have taken fire," he told Reuters.
Bociurkiw could not say who was responsible and there was nothing to suggest the monitors had been deliberately targeted. "It all points to the fragility of the ceasefire," he said.
(Additional reporting by Anton Zverev in Donetsk and Pavel Polityuk in Kiev; Writing by Richard Balmforth; Editing by Crispian Balmer)