When it launched, Oasis Trust boss, Steve Chalke, said it represented a “revolution in youth justice” and promised “relentless love” instead of punishment after the the government and the NHS ploughed £40million into renovating the former Medway Secure Training Centre site.

But the institute was thrown into turmoil and forced to temporarily close around a year after it opened when safety concerns were raised by Ofsted.

The watchdog found some doors were so damaged that they could not lock, while staff reported the youths had “free rein” of the centre. Police were called in following reports an inmate “went berserk” and allegedly attacked three female members of staff.

Oasis Restore said at the time the problems stemmed from the “built environment and the effectiveness of internal doors”.

It has now been revealed the government has handed an extra £3million to pay for the replacement fixtures, working out at more than £16,666 a door.

KentOnline did some digging into the local property market and found that sum could buy Medway’s most expensive house - The Gleanings in St Margaret's Street, Rochester, which is on for £2.4million.

The £600k change would also pay for 86 nights in The Ritz hotel’s signature Green Park Suite in Mayfair, London.

At any one time, there were 49 children at the school, with each inmate costing around £250,000 on average each year to house – five times more than it costs to house an ordinary prisoner in England and Wales.

And now the spending on the new doors has been met with further scrutiny.

Medway councillor Mark Joy (Con) told KentOnline that “heads need to roll” over the sums involved.

The shadow cabinet member for children’s services and education said: “I’m not surprised by the spending, as this is just the normal spending of government departments.

“Getting a government contract is just a licence to print money.

“In the private sector, if something does not work, it’s the supplier that picks up the tab, but in this case, it’s the taxpayer.

“Government on all levels needs to start acting responsibly. They need to start thinking like it is their money they are spending, and whether it is being spent correctly.

“Heads need to roll for this.”

Callum McGoldrick, investigations campaign manager at the TaxPayers' Alliance, says the expenditure is “beyond a parody”.

He said: “Taxpayers were told this experiment would transform youth justice, but instead it’s become another costly failure where violent offenders are running riot and staff are under attack."

A spokesman for the Ministry of Justice (MoJ) said: “We’re working with Oasis Restore to fix the doors and get the school back up and running as quickly as possible.

“We’re also offering additional support, focused on staff training and safeguarding, as they prepare to reopen.”

The latest revelation came during a Public Accounts Committee meeting on Thursday, October 23.

Chair of the committee MP Sir Geoffrey Clifton-Brown (Con) said he was “amazed” that no one had spotted that the previous doors “could be easily kicked through”.

During the session, the MP for North Cotswolds quizzed MoJ permanent secretary Dr Joe Farrar on the progress of the centre.

Dr Farrar said: “The doors were not doors to places where people slept, but they were doors to corridors, dining areas, kitchens, visit rooms and education rooms — they were internal doors.

“They had been used before in a secure setting, and they were tested, but when they were used in this setting, they proved not to be as effective as we would like.

“We are making sure that we do thorough testing of all new doors, and we are obviously having to create a new door system.

“We will start to introduce the new doors into the site shortly.”

She added that the government hopes to reopen Oasis Restore in March next year.

It comes after staff have told a Channel Four investigation how there was rising disorder, assaults, broken doors and weapon-making.

One told the network: “It was meant to be groundbreaking and had the potential to be fantastic, but what was sold as a dream has turned into a nightmare.

“It’s a very unsafe environment for the children and the staff.

“Every internal door in the place has been kicked through, so the children virtually have free rein around the building.”

Data from a freedom of information request also showed the extent of the violence prison guards and staff faced.

A total of 66 incidents of self-harm were reported, while there were 31 assaults carried out by young people on staff between May last year and March this year.

Staff used restraint on those held in the facility 118 times during the same time frame.

The MoJ said all incidents, including those involving assaults, self-harm, or weapons, are thoroughly reviewed to ensure appropriate support for children and to embed learning across the service.