Pro-Russian separatists in Donetsk have said the city has seen the most severe Ukrainian artillery fire since the beginning of the war.
Four people have been killed and at least 23 injured, according to local media reports on Monday.
A maternity hospital in the city caught fire, but no one was injured, it said.
These claims could not be independently verified.
In order to protect the city and the Donetsk People's Republic, more troops from "allied forces," meaning the Russian army, were needed, the head of the self-proclaimed republic, Denis Pushilin, was quoted as saying by the Donetsk News Agency (DAN).
Russian-backed separatists have been controlling large parts of Donetsk province as well as neighbouring Luhansk province, which make up the region known as the Donbass in eastern in Ukraine, for years, proclaiming the so-called Donetsk and Luhansk People's Republics in 2014.
