"More than 300 trial testimonies and witness statements have already been collected, describing specific crimes and misdeeds that took place in connection with Russia's attack on Ukraine," Zbigniew Ziobro told reporters on Wednesday.
Ziobro, who also serves as Poland's prosecutor-general, was speaking during a joint press conference with the chief prosecutor of the International Criminal Court, Karim Khan, in Medyka on the Polish-Ukrainian border.
Khan earlier on Wednesday visited Ukraine and held virtual meetings with President Volodymyr Zelensky, the Reuters news agency reported.
"I was pleased to hold important exchanges with the president while in the country," Khan said in a Twitter post.
"We agreed all efforts are needed to ensure international humanitarian law is respected and to protect the civilian population," he added.
Khan in early March confirmed he was opening an investigation into possible war crimes committed in Ukraine, following a request from 39 of the court's member states.
Meanwhile, Poland's Ziobro told reporters earlier this month that he had "ordered Poland's prosecution service to open an investigation into the crime of aggressive war" against Ukraine.
Polish Foreign Minister Zbigniew Rau told the United Nations in early March that Russia's authorities were showing contempt for human rights in their assault on Ukraine and its people.
Source: IAR, PAP, Reuters