People in Donetsk say overnight shelling damaged buildings in a residential area, despite a ceasefire agreement between Ukrainian government forces and pro-Russian separatists.
They say a centre for children suffering from cerebral palsy was partly destroyed, along with several homes.
The city is held by rebels; government forces hold the airport.
Both sides blame each other for ceasefire violations in general, but officials maintain the truce is broadly holding.
“Overall the situation today remained stable. Each side on the whole respects the ceasefire. This is the first relatively calm day in eastern Ukraine. But in the meantime the terrorists are reinforcing their positions,” said Ukrainian defence spokesman Andriy Lysenko.
The Russian foreign minister – on a visit to Mali – said he hoped talks would begin soon on the status of eastern Ukraine, one of the ceasefire accord’s most sensitive points.
Sergei Lavrov called on the West to keep Kyiv in check:
“Western countries must not give ‘carte blanche’ to the Ukrainian authorities allowing them to act however they like for months ahead, forgetting the fact that implementing the agreement is the key condition to the firm resolution of any conflict,” he said.
Five Ukrainian soldiers have been killed in the past four days, according to the military in Kyiv, underlining the strains to the ceasefire.
It is part of a peace plan designed to end the five-month-old conflict.
Euronews correspondent in the Ukrainian capital, Sergio Cantone said:
‘‘When sporadic clashes take place during a ceasefire, either the two sides are testing each other’s nerves and trying to influence the negotiations, or – according to the more sceptical view shared by many Ukrainians – one of the two sides is preparing something bigger which will go beyond the current front line.’‘