An inquiry has been launched into how an undercover reporter was able to get a job at the top-security prison holding Soham murders suspect Ian Huntley.
Ian Huntley is currently at HMP Woodhill
The News of the World's David McGee said he got a job guarding Mr Huntley, despite giving the authorities a false address, CV and reference.
He took several photos of Mr Huntley in his cell, which were published in the newspaper, and said he had had several conversations with him.
The Prison Service has come under fire for the apparent failure of security vetting, which opposition MPs have said was unacceptable.
There's a series of things that have clearly gone completely wrong
Lib Dem spokesman Simon Hughes
Liberal Democrat home affairs spokesman Simon Hughes said: "There's a series of things that have clearly gone completely wrong.
"We need to know that the prison service has got its act together."
Shadow Home Secretary Oliver Letwin said:
"I don't suppose any system for checking on who you employ will be perfect, but this does sound as if... the checking of data and references is not what it should be.
"It is also odd that he was able to take so many photographs without any of his colleagues noticing."
The Prison Service has asked the police to investigate if the reporter broke the law by using bogus references to get the job.
"We've asked Thames Valley Police to investigate the possibility
that any criminal offence was committed," said a spokesman.
Mark Leech, editor of the reference book the Prisons Handbook, called for the resignation of Peter Atherton - the deputy director general of the Prison Service - who is responsible for security.
"It is time for the Prison Service to show it is serious about security in our maximum security prisons and do so in a way that leaves no doubt about the serious nature of these disasters.
"It's time for Peter Atherton to hang up his keys and accept he is not up to the job," he said.
The Prison Service said it was "very concerned" at the claims and had begun a top-level inquiry.
"The deputy director general has commenced an investigation which will be
conducted by a senior manager from the prison service and will report to
ministers as soon as possible."
Prison officers' representatives said the story highlighted wider problems about lack of resources and staff shortages in the service.
Brian Caton of the Prison Officers' Association
said: "We are cutting corners every day of our working lives.
"We've got far too many prisoners in prison, and we've got insufficient resource in the way of prison officers, trained prison officers, to deal with it.
"We've got to also look at the balance between how long prison officers have served, and whether it's right for them to serve at a prison that holds very high-profile prisoners."
They don't pay prison officers anywhere near the wages they should do
Prison Officers' Association
Mr McGee said he had "simply called up" the prison and asked for a job.
Within 13 weeks of starting training, he said, he was the sole guard minding Huntley on two occasions.
Mr McGee said the prison authorities had failed to check his false address or bogus references, or his job in "a long-defunct firm", before offering him the position.
They also failed to spot the word "journalist" stamped in a passport which he used as proof of
"At each point in my investigation I felt certain that there must be a vetting procedure that would expose the flaws in my application. But it kept moving forward, stage to stage, with no trouble at all.
"The camera I smuggled in could easily have been a small explosive or a
knife," he wrote.
A separate inquiry into the prison is already under way, after Huntley was taken ill after apparently taking a drugs overdose in a suicide attempt - despite being on suicide watch.
The Prison Officers Association had also blamed that incident on staffing pressures, which meant
officers with no medical training were responsible for prisoners taking their medication.
Mr Huntley denies murdering Holly Wells (left) and Jessica Chapman
Mr Huntley, 29, is on remand awaiting trial for the murders of 10-year-olds Jessica
Chapman and Holly Wells in Soham, Cambridgeshire, last year.
Mr Huntley, who denies two charges of murder, is due to go on trial in October with his girlfriend Maxine Carr, also of Soham.
She denies two offences of helping an offender and a charge of attempting to pervert the course of justice.