The bodies of hundreds of people were found in Izium, a city in the Kharkiv region that was reclaimed from the Russians last week.

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A Ukrainian soldier is standing on top of an abandoned Russian tank.

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According to the Ukrainian government's Centre for Strategic Communication, there were more than 400 bodies found in the graves.

The investigation into the graves has begun and more information will be available on Friday, according to the Ukrainian President.

According to an Interior Ministry advisor who traveled with Zelensky to the city, around 1000 bodies have been found in Izium.

Russia has denied committing war crimes in the country.

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The scene in Izium is worse than the one in Bucha, where 458 people were found dead in April, according to Gerashenko. After Russia withdrew from the city, many bodies were found in the streets or in makeshift graves, and the New York Times documented Russian forces torturing, raping and executing Ukranian civilians. Mariupol, a southeastern city that was under siege for months before being occupied by Russia, has been accused of being the location of hundreds of civilians' bodies being deposited.

Izium was under Russian control for more than six months but was reclaimed by the Ukrainians last week in one of the biggest blows to Russia in the war. On Monday, Ukraine said it had reclaimed some 20 towns and villages in just one day in a burst that appeared to catch Moscow off guard. According to the Associated Press, some weapons and equipment were left behind after the Russian troops left. One of the biggest defeats of the offensive was the loss of Izium, as the city became an important supply hub for the eastern forces.

The military says it has reclaimed several towns and cities in the past day.