Britain said on Friday it was sending experts to help Ukraine with gathering evidence and prosecuting war crimes, with a team due to arrive in Poland in early May.
Ukraine says it is investigating some 7,600 potential war crimes and at least 500 suspects following Russia's 24 Feb invasion of its neighbour.
"Russia has brought barbarity to Ukraine and committed vile atrocities, including against women. British expertise will help uncover the truth and hold (Russian President Vladimir) Putin's regime to account for its actions," Foreign Secretary Liz Truss said.
The announcement comes as Truss travels to The Hague to meet with International Criminal Court President, Judge Piotr Hofmanski, and her Dutch counterpart Wopke Hoekstra.
"The specialist team will assist the Ukrainian government as they gather evidence and prosecute war crimes and will include experts in conflict-related sexual violence," said a foreign office statement.
Moscow calls its actions a "special operation" aimed at degrading Kyiv's military power and protecting Russian-speakers living in the east of the country.