The Justice Secretary is seeking “urgent clarification” on prison security after an undercover journalist raised concerns about a jail in Bedford.

An investigation by The Times newspaper saw a journalist hired as a temporary worker at HMP Bedford, where he claimed he had not gone through a full vetting process, was able to enter the prison without being properly searched, and heard junior staff were being used for duties only fully trained prison officers should undertake.

Following publication of the investigation, Alex Chalk, the Lord Chancellor, has sought reassurance on some of the issues raised.

A spokesperson for the Ministry of Justice (MoJ) said: “This reporter was employed briefly as a temporary agency worker at HMP Bedford with restricted access and duties limited to escorting prison contractors, but the Lord Chancellor is seeking urgent clarification from the Prison Service that the vetting process for such workers is appropriate.”

Reporter Paul Morgan-Bentley was hired in February through an agency as a prison contractor escort, commonly known as an operational support grade (OSG) escort, who are not subject to the full vetting process unless they remain in post for more than three months.

According to the MoJ, OSG escorts are subject to an abridged vetting process, including a check to make sure they have no criminal record, and they are not given keys for cell doors.

In his eight days at HMP Bedford, Mr Morgan-Bentley said there were two days when security equipment at the jail’s entrance was unmanned, and on other days staff had not been properly trained in how to use the equipment.

The MoJ did acknowledge that the airport-style security was sometimes unmanned when staff were assigned to other duties, adding visitors and staff were still regularly and randomly searched when entering prison.

The MoJ spokesperson said: “The enhanced airport-style security in place at HMP Bedford and other closed jails is there solely due to this Government’s £100 million investment in tough new controls – including rolling out X-ray scanners, tightening staff searches and recruiting hundreds more drug detection dogs to make our prisons safer.”

They added: “We deliberately do not set out when it will be in operation in order to provide regular spot checks.

“However, in February it was used 91% of the time at HMP Bedford.”

The department also admitted junior staff at HMP Bedford had escorted inmates without a prison officer present, and said this was “being addressed with leaders” at the jail.

While Mr Morgan-Bentley was working at HMP Bedford, the facility was the subject of a damning inspection report from the prisons watchdog.

Chief inspector of prisons Charlie Taylor said the “filthy” conditions at HMP Bedford were some of the worst he had seen amid warnings that levels of violence remained “very high”, with the number of assaults on staff “among the highest in the country”.

The category B prison, which can hold around 400 inmates, has a history of problems including riots in 2016.

It was put into emergency measures following the inspection and the MoJ said improvements were already under way.

Labour’s shadow justice secretary Shabana Mahmood demanded “urgent reassurance” from ministers on how they would “fix these appalling breaches of security”.

She said: “This is an absolutely shocking report. The Conservatives’ failure to keep prisons secure is a threat to security and is putting the public at risk.

“Rushed vetting for recruits and no-one manning security scanners are particularly outrageous in a prison that could be housing murderers and rapists.”