Marseille Les Baumettes prison scandal
One of the photos of inmates at Marseille's Les Baumettes prison that were uploaded on FacebookMDR Baumettes/Facebook

French authorities have opened an investigation after inmates at one of the country's most infamous prisons were seen flashing drugs, cash and mobile phones to the camera in photos uploaded on social media.

The pictures depicting convicts at Marseille's Les Baumettes prison engaging in unauthorised activities were first posted on a Facebook page named "Dying of Laughter at Les Baumettes".

In one image a detainee is seen lying on a cell bed showcasing several mobile phones - which are banned inside prison - as well as numerous €50 (£40) notes.

Others depict a piece of hashish and a joint on a table, and inmates smoking shisha or posing for group photos.

The page gathered more than 5,000 likes before it was spotted by local media and subsequently shut down.

"Upon discovering the page, we took immediate action by opening an investigation and notifying the prosecutors in Marseille," Philippe Perron, the head of France's Prison Administration, told AFP.

It was replaced by a second page with the same name but fewer photos that reached some 3,000 likes in a few hours.

Perron said the page had been set up by someone outside the prison, with a guard suggesting to local media it was the work of a recently released former inmate.

The photos angered prison guard unions that denounced what they said was the "holiday-resort atmosphere" created in detention facilities across the country by the lack of a sufficient number of jailers.

The case also underscored the problem of overcrowding in France's prisons. Les Baumettes holds 1,800 inmates but was designed to house a maximum of 1,200.

Last year guards at the jail staged a protest saying they needed an additional 50 operatives to adequately run the facility.