The cost to build two CalMac ferries at the Ferguson Marine shipyard has soared by nearly £100m.

According to new Ferguson Marine estimates,   the costs are now forecast to rise by nearly £100m from around £240m to nearly £340m.

The overall cost includes a lost £82.25 million paid by Scottish Government-controlled ferry owners Caledonian Maritime Assets Limited (CMAL)  to Jim McColl-controlled Ferguson Marine under the original contract plus £45m in ministerial loans that have also been lost.

A letter from Ferguson Marine has confirmed that the costs since the Scottish Government took control of the yard when it went into administration in August, 2019, has risen from around £112m when Audit Scotland examined the procurement process in March to £209.6m 

If the  nationalised shipyard meets its target and contingencies are not needed they would save £13.2m, meaning the overall cost would come down to £327m

Both ferries were due to cost just £97m - and were to be paid for by CMAL by repaying a Scottish Government loan over 25 years through using revenue it generates from the fees it gets from the lease of vessels like CalMac’s ferry fleet and harbour access fees.

But it was revealed  that as part of the Scottish Government's special deal to allow Ferguson Marine to win the contract in the wake of CMAL's concerns over a lack of financial guarantees from Jim McColl's firm, the loan was wiped out.

The £82.5m that was drawn down was "eliminated" after the firm went into insolvency in August, 2019.

The special deal came after CMAL registered concern that it were being put at commercial risk if Ferguson Marine became insolvent or failed to deliver on the ships without the full refund guarantees.

Mr McColl, one of Scotland’s richest men, had acquired Ferguson Marine out
of insolvency 11 months before becoming the preferred bidder in the project.

The Herald: First Minister Nicola Sturgeon with Jim McColl at a launch ceremony for the liquefied natural gas passenger ferry MV Glen Sannox, the UK's first LNG ferry, at Ferguson Marine Engineering in Port Glasgow. PRESS ASSOCIATION Photo. Picture date: Tuesday

Deputy First Minister John Swinney said there would be a “rigorous approach” taken to scrutinising “this request for additional funding”.

He said that he wanted to "minimise any further costs to the public".

It came as it emerged the two  at the centre of Scotland's ferry fiasco will not come into service till 2014.

Details of the further delays has come as ministers refused to commit to a police probe into suggestions the process of awarding the disastrous £97m Scottish ferries contract may have been rigged.

A letter from Ferguson Marine's chief executive David Tydeman reveals that plans to have the two lifeline vessels in place next year have had to be pushed back.

Issues with building the ferries mean that Glen Sannox was originally not to see service till between March and May 2023 at the earliest, while Hull 802 was not due to set sail till between October and December 2023.

Now Mr Tydeman has said that moving resources to deal with issues with Glen Sannox means that a handover of Hull 802 is not now planned until the first three months of 2024.

He indicated that the target for completion of Glen Sannox was April, 2023.

He said: "The increase in work scope on [Glen Sannox] identified over the past three months has diverted resources from 80s which has put pressure on the delivery date for 801..."

Mr Swinney added: “Our priority is to undertake our own due diligence and this will be supported by external, independent financial advisors to ensure a rigorous approach is taken to scrutinising this request for additional funding.

“Let me be clear that no decision on any potential further investment has yet been made, and will not be made until this work has been completed. We are fully committed to financial transparency and I will update the Scottish Parliament in due course.

“The Scottish Government remains committed to a sustainable future for the shipyard and supporting the island communities which rely on this type of vessel, while safeguarding the hundreds of jobs for workers on the Clyde and the apprentices that are now beginning a career in shipbuilding at Ferguson Marine.”