An officer at a Salford prison was the target of a horrific attack.
The victim had a mix of boiling water and sugar poured over them.
They required hospital treatment for burns.
One source said: "It is known as napalming amongst inmates, and very painful."
The incident took place earlier this month at Forest Bank prison in Agecroft and Greater Manchester Police have launched an investigation.
A spokesman for Sodexo, which runs the privately operated jail, said: “An assault on a Prison custody officer is currently under a police investigation so it would be inappropriate to comment further.”
Another source said: "The member of staff spent time in hospital with burns after having a bucket of hot water thrown on him by a prisoner."
Earlier this month the Manchester Evening News reported how masked men on motorbikes torched a car outside the main entrance of Forest Bank.
Footage from the scene shows three men stood around a vehicle which seems to have been pushed up to the gates of the Salford prison.
One of the group is bent down and starts a small fire just outside the car before leaning in and setting the interior of the vehicle alight.
Two of the men then climb onto a bike while the other runs towards the person filming.
Police were called at around 9pm on Thursday November 5th 2020 to a report of arson at Forest Bank prison, Salford.
GMP confirmed offenders set fire to a car outside the prison before leaving on two motorcycles.
No arrests have been made and enquiries are ongoing.
The Category B prison, run by Sodexo Justice Services, has capacity for 1,460 inmates.
