KENNETH MacAskill has claimed officials told him barefaced lies about the cost of privately financed prisons and it took “stand up fights” with staff to change the system.

The former Justice Secretary denounced private finance deals as “a collective lie in the corridors of power and the corporate boardroom”.

Writing in The Herald, he says: “The public purse was being filched for private profit”.

The remarks come amid an intense public debate about the use of private finance initiative projects and public-private partnerships (PFI/PPP) in the wake of the collapse of the infrastructure and outsourcing giant Carillion last week.

READ MORE: Time to expose the lies behind the clamour for private prisons

UK Labour leader Jeremy Corbyn called it a watershed moment in politics, while Scottish leader Richard Leonard said he would “boot out” PFI deals from the NHS.

The UK’s National Audit Office also said taxpayers will be forced to hand over nearly £200bn to private contractors under PFI deals for at least 25 years.

The auditors found privately financing projects could be 40 per cent more expensive than using government money, but there was little evidence of financial benefits in 700 projects.

PFI was started under John Major’s Tory government in 1992 and accelerated after New Labour came to power in 1997 under the guise of PPP.

Mr MacAskill, the SNP Justice Secretary from 2007 to 2014, said his main experience of PFI/PPP involved private prisons, such as Kilmarnock and Addiewell in West Lothian.

He said he was “bitterly disappointed” not to have reversed the Addiewell PFI/PPP, which was built for £80m in 2006, but which will cost taxpayers almost £1bn over 25 years.

READ MORE: Time to expose the lies behind the clamour for private prisons

Penalty clauses agreed by the previous Lab-LibDem coalition made changing the contract “impossible”, he said, but he did stop PPP being used for Low Moss at Bishopbriggs.

He said Low Moss had been a “tipping point”, and if PPP had been used, there would have been no stopping the prison service “falling into private hands”.

He said officials had also hidden the cost of Addiewell, denying its true £1bn cost.

“What concerned me was the lies I had been told,” he said. “Not only was the figure repudiated by those then in senior positions, but I was even told I couldn’t say that private prisons were more expensive… that the state model was cheaper.

“Stand up fights were required with senior staff to deliver change.”