The estimated death toll in the Ukraine conflict nearly doubled to at least 2,086 as of Aug. 10 from 1,129 on July 26, the United Nations human rights office said on Wednesday.
"This corresponds to a clear escalating trend," UN human rights spokeswoman Cecile Pouilly told Reuters in response to a query.
On average, more than 60 people a day have been killed or wounded since fighting began in mid-April in eastern Ukraine, rising to at least 70 people a day in the first week of August, she said.
Nearly 5,000 have been wounded to date. The figures for casualties include Ukrainian soldiers, armed groups, pro-Russian militants and civilians, but are "very conservative estimates," Pouilly said.
"For instance, civilian casualties are likely to be under reported, due to the continuing insecurity which prevents affected people from getting access to medical aid...and because communication channels have been disrupted," she added.
It was not clear whether Russian soldiers were included in the UN estimates for casualties which were based on information received from Ukrainian authorities as well as local medical facilities, Pouilly said. "We have no breakdown on nationalities or (civilian or military) status," she said.
Violence continues in eastern Ukraine
Twelve Ukrainian nationalist fighters, battling a pro-Russian insurgency in eastern Ukraine, were killed early on Wednesday and an unknown number taken captive when rebels ambushed their bus, a spokesman for their group said.
The separatists opened fire on the bus, that was taking the men to fight just outside the rebel-held city of Donetsk, at the nearby village of Mandrykino, said a spokesman for Right Sector, extreme nationalists who are supporting government forces.
"They were taking part in a military operation early this morning near Donetsk and were ambushed. Twelve Right Sector fighters were killed," spokesman Artem Skoropadsky told Reuters.
It was the group's biggest single loss of life since violence erupted in Ukraine's Russian-speaking east in April, he said.
Ukraine accuses Russia of cynicism over convoy
Meanwhile, Ukraine denounced Russia's dispatch of a humanitarian aid convoy now advancing towards the border as an act of unbounded cynicism serving pro-Russian separatists, and the UN said the death toll in fighting had doubled in the last two weeks to over 2,000.
Kyiv said the trucks would not be allowed to pass.
"First they send tanks, Grad missiles and bandits who fire on Ukrainians and then they send water and salt," Prime Minister Arseny Yatsenyuk said at a government meeting on Wednesday.
The comments reflected suspicions in Kyiv and Western capitals that passage of the convoy onto Ukrainian soil could turn into a covert military action to help pro-Russian separatists now losing ground to government forces.