A man has been arrested after a prisoner was found dead in his cell with a slashed throat at HMP Thameside in Greenwich.
Police were called at 2.37am to the prison in the early hours of Sunday morning after prison wardens discovered the dead inmate.
Officers have not yet informed the next of kin.
A man in his late 30s has been arrested on suspicion of murder.
A Metropolitan Police Spokesperson said: "Police were called at 02:37hrs on Sunday, 12 January to HMP Thameside in Greenwich after an inmate was discovered suffering from a slash injury to his throat.
"The man, aged in his 40s, was pronounced dead at the scene by LAS.
"Officers are working to inform his next of kin. Formal identification and a post-mortem examination will take place in due course.
"A man, believed to be aged in his late 30s, has been arrested on suspicion of murder and taken into custody.
"Officers from the Specialist Crime Command have been informed and enquiries into the circumstances continue."
