Ukraine has unearthed two more mass graves containing the dead of hundreds of people in the northeastern town of Izium, which Kyiv reclaimed from Russia earlier this month, according to Ukrainian President Volodymyr Zelenskiy.

Zelenskiy made his remarks in an interview with CBS released late Sunday, in which he also urged for continued sanctions pressure on Russia, whose troops were routed in northern Ukraine this month in a quick counteroffensive.

Russian authorities did not immediately comment on Zelenskiy’s assertion about the discovery of two more burial sites. Moscow regularly denies committing atrocities in the war in Ukraine or targeting civilians.

“Today I received more information… They found two more mass graves, big graves with hundreds of people… We’re talking about (the) little town of Izium,” Zelenskiy said.

“The sanctions need to continue. These sanctions will have political impact, as well as financial impact.”

After the months-long Russian occupation, Ukrainian authorities uncovered a large burial site next to a cemetery in a wooded area in Izium earlier this month, and launched an investigation into the circumstances of the deaths.

Last week, they finished exhuming the bodies of 436 people. The majority of them appeared to have died violent deaths and there were preliminary indications that 30 of them had been tortured, the regional governor said.

Seventeen soldiers were also exhumed from a mass grave at the site.