"We should collect and protect everything in the right way. It should be acceptable evidence in any court," Iryna Venediktova said.
Mandelblit said that Israel's significant investment in probing its own alleged war crimes would protect it from outside legal cases.
Support like that which Israel received from the Biden administration during last year’s war in Gaza cannot be taken for granted anymore.
Moscow denies committing war crimes in Ukraine or targeting civilians during a war that has killed thousands.
ICC prosecutor Karim Khan and the Prosecutors General from Lithuania, Poland and Ukraine signed a deal for the international war crimes tribunal's first-ever participation in an investigative team.
The International Criminal Court's chief prosecutor said last month he had opened an investigation into possible war crimes in Ukraine.
Ali Muhammad Ali Abd-Al-Rahman is accused of overseeing thousands of pro-government Janjaweed fighters responsible for persecution, murder, rape and torture.
Former Sudanese president Omar Hassan al-Bashir, who faces ICC charges of orchestrating genocide and other atrocities in Darfur, was deposed during a popular uprising in 2019 and remains in prison.
Khan opened a formal inquiry into war crimes and crimes against humanity in Ukraine on Feb. 28, four days after Russia invaded its smaller neighbor.
The grant raised concerns for the potential of abuse by organizations to act against Israel via BDS and international law tribunals.