The Edinburgh trams inquiry could result in criminal prosecutions, according to its chair Lord Hardie.

The judge said that while the inquiry lacks the power to determine criminal or civil liability, “that does not mean that nobody will be prosecuted as a consequence of their involvement in the project”.

He is in the process of taking evidence from those involved in the fiasco, including members of the public and has called on others to come forward.

The tram system was meant to cost £375 million and run to 15 miles by 2011. However, when it finally opened in 2014, the route was only nine miles long and had cost a staggering £776m.

The final bill is expected to be in the region of £1 billion.

Delays, budget overruns, contract oversight and other issues all fall within the remit of the inquiry.

Lord Hardie said: “Any question of prosecution will ultimately be a matter for the Lord Advocate and Crown Office and Procurator Fiscal Service (COPFS), and their decision will depend upon the availability of evidence supporting such a decision.

“As far as I am aware, neither the Lord Advocate nor COPFS has determined that nobody will be prosecuted.

“Indeed, it might seem to be premature to express such a view without considering the terms of the inquiry report which will be written after the conclusion of the evidence sessions in public.

“Furthermore, any question of civil liability must be determined by an appropriate court, having jurisdiction to do so.”

He added: “Many of these issues, particularly the consequences of the failures mentioned above, involve the co-operation of members of the public, who had direct experience of them.

“That co-operation is essential if lessons about avoiding similar consequences can be learned and implemented for future projects of a similar nature.

“This is not merely an academic exercise.”

It was reported last month that the inquiry itself has already cost more than £3.7m.