A prisoner has died after his throat was slashed inside a privately-run jail.
The inmate, in his 40s, was attacked at HMP Thameside in Greenwich, south-east London, at about 02:30 GMT on Sunday, the Met Police said.
He was pronounced dead at the Category B prison, which is run by the private company Serco and holds about 1,200 inmates.
A male prisoner in his late 30s has been arrested on suspicion of murder.
Scotland Yard said the inmate was discovered “suffering from a slash injury to his throat” and he was pronounced dead at the scene by paramedics.
“Officers are working to inform his next of kin. Formal identification and a post-mortem examination will take place in due course,” a spokesperson added.
Trish Mitchell, Serco contract director at HMP Thameside, said: “Sadly there has been a death at HMP Thameside. A man has been arrested and our staff are working closely with the police.”
HMP Thameside serves courts in east and south-east London and has an “extremely high turnover of prisoners” with the average stay a “mere 36 days”, according to an inspection report in 2017.