These chilling images purportedly show prisoners from HMP Pentonville brazenly brandishing a deadly weapon – weeks after a fatal stabbing at the embattled jail.

Islington Gazette: The Prison Service is investigating the authenticity of images of prisoners apparently brandishing a knife inside PentonvilleThe Prison Service is investigating the authenticity of images of prisoners apparently brandishing a knife inside Pentonville (Image: Archant)

The photographs, obtained exclusively by the Gazette from a source at Pentonville and apparently taken behind bars at the Caledonian Road jail, appear to show a stash of drugs wrapped in cellophane, a hoard of smart phones and a knife.

Security was ramped up at the prison following the knife killing of inmate Jamal Mahmoud on October 18.

But the Gazette understands the contraband has been smuggled in since, in the latest in a line of security breaches.

We have passed the information onto prison authorities, who are investigating to establish the authenticity of the images.

Islington Gazette: The knife can be seen more clearly in this imageThe knife can be seen more clearly in this image (Image: Archant)

A Prison Service spokesman said: “There is no evidence to suggest these pictures were taken inside a prison.

“However, we would urge the Gazette to share any information that could help us investigate this further.”

Islington South and Finsbury MP Emily Thornberry said the pictures, if true, were “absolutely shocking”.

She said: “I have grave concerns about the safety of staff and inmates at Pentonville and I have been saying for more than a year that the walls are not secure.”

Islington Gazette: This picture appears to show a stash of drugs inside Pentonville prisonThis picture appears to show a stash of drugs inside Pentonville prison (Image: Archant)

She has called for ministers to “get a grip” and decide whether to close the prison.

The Gazette has been told by a well-placed source that drugs and mobile phones are rife within the jail.

It is understood smartphones sell for up to £600 and the synthetic drug, Spice, can fetch £500 or £600 an ounce.

One source said drones are flown in as often as twice weekly.

Islington Gazette: Mobile phones purportedly inside Pentonville prisonMobile phones purportedly inside Pentonville prison (Image: Archant)

Cllr Paul Convery, who lives a few hundred yards from the jail, said: “I’m horrified [if] weapons are still in the prison. It’s quite shocking that security could still be so lax. I just don’t think the prison service has grasped the problem.”

He called for inmate numbers to be reduced by 350, for windows and nets to be made secure, and for new management to be brought in.

“Until those things are done the prison is a dangerous place both on the inside and outside,” he said.

The Gazette last month reported on holes in prison security netting at Pentonville, allegedly used to smuggle packages into the jail, which prison authorities say have since been fixed.