In the centre of Donetsk, rebel forces pitched tents outside the regional administration building on Tuesday in a bid to recruit volunteers.
The move follows Monday’s heavy losses sustained by the separatists in the battle for the city’s airport.
One rebel recruit in Donetsk accused Ukrainian government forces of shelling civilians.
‘‘We will defend our city, we will fight till the end. Shooting mortars at ordinary peaceful people is wrong. A lot of civilians suffered at the train station yesterday. They were fired upon with mortars,’‘ he said.
In addition to the fighting in Donetsk violence has also erupted near east Ukraine’s other main city Sloviansk, with reports of at least four killed and one wounded.
Russia’s ITAR-TASS news agency said the dead had been shelled by Ukraine’s military, a claim denied by the Defence Ministry in Kyiv.
It insisted its forces were not active in the area at the time and has blamed insurgents for the deaths.