The UN's human rights office says the number of people who have been killed in eastern Ukraine appears to have doubled in the last two weeks, as the government warned a Russian humanitarian aid convoy will not be allowed to enter Kharkiv in the east of the country.
A spokeswoman for the office said "very conservative estimates" show the death toll has risen to at least 2,086 people from 1,129 on 26 July.
At least 4,953 others have been wounded in the fighting since mid-April. On average, she said, more than 60 people a day have been killed or wounded as part of "a clear escalating trend" of violence.
The figures come as the aid convoy stopped at a military base in Voronezh after being driven there from the outskirts of Moscow.
In a Facebook post earlier today, Ukraine's Interior Minister Arsen Avakov had warned "no Putin 'humanitarian convoy'" will be allowed across the territory of Kharkiv region and condemned the dispatch of convoys as a “provocation by a cynical aggressor”.
Prime Minister Arseny Yatseniuk also denounced the dispatch as as an act of Russian "cynicism".
He told a government meeting: "The level of Russian cynicism knows no bounds. First they send tanks, Grad missiles and bandits who fire on Ukrainians and then they send water and salt."
Andriy Lysenko, a spokesperson for Ukraine's National Security and Defence Council, said on Tuesday the Russian aid consignment from Moscow had not been certified by the Red Cross and as such would not be admitted.
The trucks departed from near Moscow on Tuesday morning, and were expected to reach the eastern Ukraine border within one or two days.
Thousands of people are believed to be desperately short of food, water and medical aid due to the fighting, which has seen more than 1,300 people killed.
The aid is most urgently needed in the largely rebel-held province of Luhansk. Its capital had a pre-war population of 420,000, and the 250,000 remaining have been without electricity or water supplies for eleven days.
On Monday, Russia announced the aid mission, which it said would be sent in co-operation with the International Red Cross.
However, Andre Loersch, a spokesperson for the International Committee of the Red Cross mission in Ukraine, said the organisation had “no information about the content” of the trucks and did not know where they were headed.
Ukraine crisis: Russian 'aid' convoy
Ukraine crisis: Russian 'aid' convoy
1/11 Ukraine crisis
Drivers of the first trucks of the Russian aid convoy parked in the city of Luhansk on 22 August
2/11 Ukraine crisis
An employee inspects the contents of a truck with Russian humanitarian aid in Mariupol, Ukraine on 22 August 2014
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The convoy nearing the border before it parked at a camp in Russia
4/11 Ukraine crisis
Russian convoy carrying humanitarian aid for residents in rebel eastern Ukrainian regions moving along a road in the city of Voronezh, about 530 km from Moscow, Russia
5/11 Ukraine crisis
An Ukrainian border guard checks passing cars at a checkpoint of Pletnyovka, Kharkiv region on Ukraine-Russia border, where Russian humanitarian convoy is to cross the border
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Ukrainian border guards stand at the Ukrainian-Russian border crossing
7/11 Ukraine crisis
Trucks of a Russian convoy carrying humanitarian aid for Ukraine are parked at the military air base outside Voronezh
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Drivers of a Russian convoy of trucks carrying humanitarian aid for Ukraine take a rest on a side of a road near the city of Yelets
9/11 Ukraine crisis
An Ukrainian soldier stands guard at a checkpoint of Pletnyovka, Kharkiv region on Ukraine-Russia border, where Russian humanitarian convoy is to cross the border
10/11 Ukraine crisis
A Russian convoy carrying humanitarian aid for residents in rebel eastern Ukrainian regions moves along a road about 50 km from Voronezh, Russia, 14 August 2014. The convoy continues to advance through Russian territory after a one-day stop in Voronezh in full coordination with and under the aegis of the Red Cross, according to Russian authorities
11/11 Ukraine crisis
The Russian convoy carrying humanitarian aid in the Voronezh region of Russia en route to Ukraine
In the last week, Ukrainian government forces have been closing in on the few remaining pro-Russian rebel strongholds in eastern Ukraine, including Donetsk - the largest rebel-held city. Hundreds of thousands of residents have been fleeing the fighting.
Ukrainian President Petro Poroshenko said he would only support an aid mission with Russia if other international bodies, including the Red Cross and the European Union, were involved.
Mr Poroshenko added that he had spoke to US President Barack Obama, who backed the international plan. The cautious support came after the West strongly warned Russia any attempt to send its military personnel into Ukraine under the guise of humanitarian assistance would be regarded as an invasion.
The Russian Foreign Ministry today dismissed claims the trucks could be a cover for an invasion as "absurd".
Additional reporting by agencies