Ukraine is reportedly preparing war crimes charges against at least seven members of the Russian military. 

The Ukrainian prosecutor general’s office told Reuters that three Russian pilots suspected of bombing civilian buildings in the Kharkiv and Sumy regions, two operators of a rocket launcher who allegedly shelled settlements in the Kharkiv region and two army servicemen suspected of murdering a Kyiv area resident and raping his wife were among those under investigation. 

UN CHIEF: RUSSIA STILL HAS 'DIFFERENT POSITION' ON WHAT IS HAPPENING IN UKRAINE

The office added that the individuals had been notified that they are suspects and that the probes are ongoing, though no charges have been filed with the court. 

Ukraine says it is investigating some 7,600 potential war crimes and at least 500 suspects.

The United Nations (UN) has also opened its own inquiry into possible war crimes. According to the agency, war crimes include targeting civilian populations, willfully killing or causing suffering and widespread destruction, among other violations.

A Ukrainian serviceman walks amid rubble in Kharkiv

A Ukrainian serviceman walks amid the rubble of a building heavily damaged by multiple Russian bombardments near a frontline in Kharkiv, Ukraine, Monday, April 25, 2022.  (AP Photo/Felipe Dana)

Notably, the International Criminal Court’s prosecution office is joining a joint investigation team set up by Ukraine, Lithuania and Poland to investigate atrocities committed during the invasion. 

Even as photos have been taken of bodies lining city streets and mass grave sites, Russia has denied targeting civilians, and Moscow has accused Kyiv of genocide against Russian speakers. 

On Monday, Russian Foreign Minister Sergei Lavrov accused NATO of "pouring oil on the fire" with its support for Ukraine. He also warned against provoking World War III and said the threat of a nuclear conflict "should not be underestimated."

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U.N. Secretary-General António Guterres – who has called for a cease-fire in Ukraine – is expected to meet with Russian President Vladimir Putin on Tuesday before visiting Kyiv later this week. 

On Tuesday, the British Defense Ministry said Russian soldiers had taken the city of Kreminna in Ukraine's Luhansk region, approximately 355 miles southeast of the Ukrainian capital. 

Luhansk Governor Serhiy Haidai said three people died after Russian shells hit a residential building in the city of Popasna.

Four people died and nine were wounded Monday after Russian shelling in the Donetsk region – the victims include a 9-year-old girl and a 14-year-old boy. Governor Pavlo Kyrylenko said Tuesday that two more people were killed and six others wounded.

In Kharkiv, regional Governor Oleh Synehubov said shelling of civilian areas killed three people and wounded seven more. Rocket strikes were also reported in the Zaporizhzhia region.

Ukraine's General Staff said the country's forces have repelled six attacks in the past 24 hours in the two regions that comprise the Donbas.

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While the U.N. human rights office said Tuesday it has counted 2,729 people killed and 3,111 injured in the fighting since Feb. 24, it acknowledges that the tally only includes confirmed casualties and that the toll is likely to be much higher. 

The U.N. refugee agency projects up to 8.3 million people will have to flee the country by year-end.

Reuters and The Associated Press contributed to this report.