Inmates 'assaulted by prison officers' in Russia
A video appearing to show Russian prison officers punching and kicking one of their inmates has been unearthed by human rights campaigners.
It is the latest in a series of scandals about how Russian police and prison officers treat those in their charge.
This month the United Nations Committee against Torture expressed deep concern about such severe mistreatment going unpunished.
Daniel Sandford's report contains disturbing images. Some sound has been removed.