Up to 13,000 Ukrainian soldiers have been killed since the start of Russia's invasion, a senior official has said.
Mykhailo Podolyak, an adviser to Ukrainian President Volodymyr Zelensky, said between 10,000 and 13,000 troops had died.
It is rare for Ukraine to give figures for casualties, and Mr Podolyak's comments have not been confirmed by the country's military.
In June he said between 100 and 200 Ukrainian soldiers were dying daily.
Last month, the most senior US general, Mark Milley, said around 100,000 Russian and 100,000 Ukrainian soldiers had been killed or injured since the start of the war.
In a video address on Wednesday, EU Commission head Ursula Von der Leyen said that 100,000 Ukrainian troops had been killed. However a spokesperson for the EU Commission later clarified that this was a mistake, and the figure referred to those both killed and injured.
Speaking to Ukrainian TV outlet Channel 24, Mr Podolyak said Kyiv was "openly talking about the number of the killed".
"We have official evaluations by the General Staff, official evaluations by the commander-in-chief [Mr Zelensky], and they range from 10,000 to 12,500-13,000 killed," he said.
He added that the number of civilians killed could be "significant". BBC News had identified about 3,600 civilian deaths as of mid-June. The figure is now likely to be much higher.
Mr Podolyak also suggested that up to 100,000 Russian soldiers had been killed since the invasion began on 24 February, and that a further 100,000 to 150,000 had been wounded, or were missing or unable to return to combat.
The BBC's Russian Service has established that at least 9,311 Russian soldiers of all ranks have been killed since the invasion on 24 February while the true death toll could be more than 18,600.
In another development, the Ukrainian military said Russia was using dummy nuclear-capable missiles to exhaust Ukraine's air defences.
Russia was using rockets designed for nuclear use without explosive warheads, Ukrainian military experts said, suggesting this might be because the country has used so many of its other missiles in massive strikes on Ukrainian infrastructure.
BBC
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