Holyrood’s public audit committee is following up on a damning Audit Scotland report.

The ships are five years late and could end up costing more than £300m.

The first minister has previously said that while former transport minister Derek Mackay approved the deal, the “buck stops” with her.

The £97m “fixed price” contract was awarded to Ferguson shipyard in Port Glasgow in 2015, a year after it was rescued by businessman Jim McColl, a prominent SNP supporter who sat on the first minister’s council of economic advisers.

The build for the two ships, Glen Sannox and the unnamed Hull 802, soon ran into trouble, with the yard going back into administration again in 2019.

It was later nationalised but neither ferry has yet been delivered.

An Audit Scotland report in March identified “multiple failings” including the lack of a “full builders guarantee”, a standard feature of major shipbuilding contracts which protects the buyer if things go wrong.

It also criticised a lack of record keeping on why the decision was made.

The Scottish government later published emails that confirmed Derek Mackay approved the deal, but in Holyrood exchanges Ms Sturgeon said that as first minister she took ultimate responsibility.

She said: “The buck stops with me and I have never tried to shy away from that on any issue. I am not defending the cost overruns or the delay to the construction of these ferries, it is completely unacceptable.”

Mr Mackay, who left government in 2020 over messages he sent to a 16-year-old boy on social media, appeared before the public audit committee in September.

He said he also took responsibility, but that he believed at the time that some of the financial risks had been mitigated by other means.

Since then, a BBC investigation has revealed a dossier of leaked documents which suggest the procurement process may have been rigged in favour of Jim McColl’s company, Ferguson Marine Engineering Ltd (FMEL).

The BBC’s Disclosure programme found evidence that FMEL was allowed to substantially modify its bid and reduce its price after the tender deadline, and that it has access to a key specification document that was not available to rival bidders.

The government’s ferries agency CMAL has said it found no evidence in its files to support the BBC allegations, and has defended the procurement process.