Investigation after prisoners post pictures of themselves enjoying cannabis, takeaways, steak and Xbox on Instagram

The pictures were taken on an illegally-possessed mobile phone inside HMP Guys Marsh

A Prison Service spokesman said: 'This behaviour is unacceptable. We will be referring this matter to the police for investigation and have had the social media profiles removed' (iStock)

An investigation has been launched after photos emerged of inmates showing off smuggled steaks and takeaways inside a prison.

The pictures - which were taken on an illegally-possessed mobile phone inside HMP Guys Marsh, near Shaftesbury, Dorset, and posted to social media - also appeared to depict drug possession.

The images emerged in a turbulent week for the Ministry of Justice after it was forced to obtain a High Court injunction to order staff back to work after a mass walkout over health and safety fears.

A Prison Service spokesperson said of the images: “This behaviour is unacceptable. We will be referring this matter to the police for investigation and have had the social media profiles removed.

“We are stepping up measures to find and block mobile phones in prisons and those found with them face extra time behind bars.”

It is believed that four of the six prisoners who were pictured in the social media posts have been moved to other prisons.

In the HM Inspectorate of Prisons' latest report, inspectors said staff had “all but lost control” of the Category C jail.

PA