German police said Saturday they were investigating several hundred potential Russian war crimes in Ukraine including political and military officials suspected of being linked to the alleged offences.
"Up until now we have received a three-digit number of leads," Holger Muench, head of the BKA federal police, told the Welt am Sonntag newspaper.
The inquiry does not only cover suspected perpetrators of war crimes but also political and military officials, he said.
"It's the most difficult part of our inquiry, intricate puzzle work," he added.
"Our clear goal is to identify those responsible for atrocities, to prove their actions through our investigations and bring them to justice," including in Germany.
The country applies universal jurisdiction which allows a foreign country to prosecute crimes against humanity, war crimes and genocide, regardless of where they were committed.
However "that may take time" because investigations linked to the Ukraine conflict are only at their "very beginning", Muench said.
The BKA is being helped in its inquiries by Germany's foreign intelligence service among others which has for instance recorded the radio conversations of Russian soldiers.
German investigators could also be sent to Ukraine, Muench said, adding however that they would need an international mandate to do so.
The UN's Ukraine commission on Wednesday confirmed receiving multiple allegations of rights abuses by Russian forces, but said it was too early to say whether they constituted war crimes.