A post mortem's likely to be done today for a prisoner who died at Auckland's Mount Eden Corrections Facility

A homicide investigation's been launched after an inmate was found dead with numerous injuries in his double-bunk cell yesterday morning.

Men's Prisons Deputy Commissioner, David Pattinson, says a second inmate residing in the cell has been secured in a single-cell during investigations.

Police say they're speaking with a man, and will work alongside Corrections.