"Over the past two months, within the de-occupied areas of the Kharkiv region, Kherson region and Donetsk region, more than 700 bodies have been discovered,” Kostin said at the weekend, as quoted by state news agency Ukrinform.
"About 90 percent of them are those of civilians," he added in a statement.
Kostin also said that more than 20 sites were found in these three regions where Ukrainian citizens were illegally detained and tortured, according to the ukrinform.net website.
In almost every city and village in the liberated Kharkiv region, law enforcement officers have found places where civilians were killed, Kostin was quoted as saying.
"We are seeing the same situation in the Kherson Oblast," Kostin added.
Ukrainian President Volodymyr Zelensky said earlier this month that investigators had uncovered more than 400 Russian war crimes in his country's southern Kherson region after the withdrawal of Russian forces.
Source: IAR, PAP, ukrinform.net