Scotland’s Transport Secretary has defended her government’s decision to essentially walk away from the chaotic Edinburgh trams project more than 16 years ago – despite being partially blamed for the fiasco by the official inquiry into the fiasco.

The Scottish Government has been accused of the “understatement of the century” after attempting to justify Transport Scotland cutting ties with delivering the project in 2007 and just having a role as a funder.

Transport Scotland re-entered the project in 2011 to help conclude the fiasco.

Lord Hardie finally published his long overdue and incredibly expensive review into the initial Edinburgh trams project in September - with the total costs of the completed line from the airport to Newhaven thought to be around £1 billion.

Read more: 'Hell on wheels': The bitter battle to complete Edinburgh's tram line

Much of the blame in the inquiry report is pointed at Edinburgh City Council and in particular, its arms-length organisation, Tie, which was responsible for tendering contracts to deliver the project.

Lord Hardie’s report hit out at a “litany of avoidable failures” that caused the project to descend into chaos.

The project was hit by severe delays and increased costs as the contracts drawn up by Tie did not have a fixed price, leading to disputes with contractors who demanded more money and downed tools, holding up the project.

In 2007, just after the SNP formed a minority government at Holyrood, John Swinney confirmed the project would receive £500 million to complete the project, but the arrangement saw Transport Scotland walk away as a partner of the project.

But Lord Hardie said that decision contributed to the mess, meanwhile he accused Mr Swinney of “pulling strings” and meddling in the scandal once Transport Scotland has washed its hands of responsibility.

The Herald: Former deputy first minister John SwinneyFormer deputy first minister John Swinney (Image: PA)

He added that “Scottish ministers withdrew the support of officials in Transport Scotland whose technical experience would have been invaluable in advising tie in the contract negotiations”.

The inquiry found that a “conduit of information” from Transport Scotland “was lost” by the Scottish Government’s decision to walk away from the project, as well as “the chance for Transport Scotland to influence directly decisions taken by the board”.

Lord Hardie concluded that in the following years, Mr Swinney was “directing” the city council “as to what should be done” to fix the crisis from behind the scenes.

But in a statement to Holyrood, SNP Transport Secretary Mairi McAllan claimed that the decision for Transport Scotland to walk away from the project “helped to avoid potential delay and increased risk”.

Read more: Analysis: Was the Edinburgh Tram Inquiry pointless? Ask the businesses

The project ended up costing £862 million for a truncated line to York Place was opened years later than planned.

In a statement to Holyrood, Ms McAllan stressed that “the only cause of failure attributed to the actions of ministers was the decision, following the debate in Parliament on June 2007 to reposition Transport Scotland as a principal funder, as opposed to a project partner”.

She said: “Setting aside for a moment the fact that this Government was very clear at the time about the risks inherent with the project and that it was others represented in this Parliament today who voted the project through, it is clear that the outcome of that vote transferred accountability to the City of Edinburgh Council and necessarily altered Transport Scotland’s relationship with the project going forward.

The Herald:

“Failure to clarify the role of Transport Scotland would have been an abdication of leadership and would have led to poor governance and confusion around roles.

“The decision to alter the governance arrangements was taken explicitly to avoid uncertainty about where leadership of the project lay, clarifying the Government’s role as principal funders and, on that basis, preventing further calls on the public purse.”

She added: “It was exactly because of the clarity and clear setting of governance boundaries that Government funding for the project remained capped at the agreed £500 million and not a penny more.

Read more: Edinburgh Tram Inquiry: John Swinney accused of meddling in crisis

“Following the parliamentary vote on the tram project, the decision to separate the roles of Transport Scotland as principal funder and City of Edinburgh Council as project lead was actually good governance and helped to avoid potential delay and increased risk.”

Asked if Transport Scotland was "fit for purpose", the cabinet secretary said it "absolutely" was, adding that she has “absolute faith” in the organisation.

Conservative MSP for Lothian, Miles Briggs, warned that “there is very little to suggest that SNP ministers have accepted their role in the project”.

He said: “The former deputy first minister, John Swinney, is mentioned 156 times by name in the report but not once by the cabinet secretary in her statement.

“The cabinet secretary states that the only ‘cause of failure’ attributed to the actions of Scottish ministers was the decision, following the debate in Parliament on June 2007, to reposition Transport Scotland as a principal funder, as opposed to a project partner.

“That is the understatement of the century.

“Lord Hardie said ‘the actions of the Scottish ministers… and the limitations imposed by them on the involvement of officials in 2007 was a serious error and resulted in the failure by the Scottish ministers to protect the public purse, insofar as their contribution of £500 million was concerned.’

“The cabinet secretary should now accept that the decision to withdraw Transport Scotland was a serious error. Yet no one in the Scottish Government has taken responsibility for that failure.”