Prosecutor of the International Criminal Court (ICC) Karim Khan has arrived in Ukraine and has started work, President of Ukraine Volodymyr Zelensky has said.

"I had a conversation with Karim Khan, the prosecutor of the International Criminal Court in The Hague. He is already in Ukraine. He has already started working," Zelensky said in a video message on Wednesday.

He also announced the start of work of the investigative group of the International Criminal Court in Ukraine, which, together with Ukrainian law enforcement officers, is already collecting all the evidence and facts of war crimes of Russian troops.

"The Russian occupiers will answer for all war crimes committed against Ukrainians. We will step up work to bring them to justice. There must be an international tribunal. And there will be one. For everything they have done against Ukraine, against our people, for every act of terrorism by Russian forces on the territory of our state," the president said.

According to him, the Prosecutor General's Office of Ukraine has already begun the relevant work.