According to the health ministry, which based its figures on bodies handled by morgues, 225 people had died in Donetsk and 45 in Luhansk.
It clarified a statement by the health minister on child deaths, saying 14 reported victims had died of illnesses.
Reports say two children were killed in the town of Slavyansk this month.
A boy aged 12 and a girl aged six died as a result of shrapnel wounds, according to a preliminary report issued by a regional health official on Tuesday.
The town of 120,000, a stronghold of the separatist rebels, has come under heavy bombardment as fighting continues between rebels and government forces.
Local residents told the BBC's Dina Newman by telephone on Wednesday that it was virtually a ghost town, with most of the town centre destroyed and most outer residential areas also heavily damaged, as well as all of the town's factories.
'Only the morgues'
Health Minister Oleh Musiy was originally quoted by media as saying 14 children had been killed during the "anti-terrorist operation".
The health ministry's revised figures include 15 women.
Mr Musiy said the death toll did not include bodies removed by the rebels themselves.
"Let me stress it once again, these are the ones [dead bodies] admitted to the morgues of various health facilities," he told Ukraine's Channel 5 TV.
"We do not have any information about the rest of them, both identified and unidentified, which the terrorists have moved out of Ukraine, because we do not co-operate either with the [self-proclaimed] Donetsk People's Republic or any other terrorist organisations."
Reporting the deaths of the two children to Ukraine's 112 news agency, Donetsk health official Ilya Suzdalev did not say when they occurred.
Ukraine's new President Petro Poroshenko has ordered the creation of humanitarian corridors so civilians can flee areas of the east hit by conflict.
Thousands of people are thought to have been displaced by the fighting.
'Fleeing by bus'
Most of Slavyansk's residents have fled though no-one knows exactly how many, residents told our reporter.
Both the separatists and some Ukrainian organisations arrange buses daily for those wanting to flee, they said.
The main worry for all evacuees is how to support themselves.
Most reportedly prefer to go to Russia, where they believe they are more likely to find jobs than in other parts of Ukraine.
The president's promise of humanitarian corridors has not impressed the residents, who worry that the "anti-terrorist operation" against their town is about to be stepped up, they said.
There are no reliable estimates of casualties from the daily bombings but personal stories from blogs and chat groups paint a desperate picture, our reporter adds.
One woman's body was reportedly found in her flat, days after her death.
She was clutching her mobile phone.
The city reportedly has no water supply and most places have little or no electricity.
Mobile phone connections are patchy and there is said to be a shortage of basic medicines.
Banks are closed and cashpoints are not working, residents said.
Pro-Russian separatists in the Donetsk and Luhansk regions, Ukraine's industrial heartland, declared independence after holding referendums last month which were deemed illegal by the government in Kiev.
The rebellion began amid the turmoil which followed the downfall in February of the elected Ukrainian President, Viktor Yanukovych, whose pro-Moscow policies sparked mass street protests in Kiev during the winter.
Source: BBC News Europe