Ukraine: How do you prove a war crime has been committed?

The way evidence is gathered to secure convictions for war crimes has been "transformed" by images and videos posted online, according to legal experts.

Prof Yvonne McDermott Rees, of Swansea University, said videos posted on social media could be used as evidence in criminal trials, and had been in both the Netherlands and Sweden in trials of returning Isis fighters.

Dearbhla Minogue, of the Global Legal Action Network, said methods had been developed by citizen journalism organisation Bellingcat to verify material.

Regarding the conflict in Ukraine, Prof McDermott Rees said content coming out of Bucha and other cities was "disturbing".