A new time limit of three months to complete criminal trials in Scotland has been set in a bid to stop lengthy cases costing the taxpayer millions of pounds.

Concerns have been raised that time is being wasted during complex cases involving fraud or multiple accused persons.

A report said lawyers' questioning was too repetitive and called on courts to maker better use of modern technology to present evidence.

It comes in the wake of the longest trial in Scottish legal history which saw Edwin McLaren, 53, convicted of a £1.6 million fraud last year.

The case heard 320 days of evidence over 20 months and is estimated to have cost £7.5 million. Some of the juror members had to receive counselling before being able to return to their normal lives.

Launching the new protocol, Lady Dorrian, the Lord Justice Clerk, said all cases should be completed within three months and that should only be exceeded in "exceptional circumstances".

The new target is a result of a collaboration between the judiciary, the Crown Office and the legal profession.

Lady Dorrian said: "It has been most encouraging to receive such broad support for the initiative, and what it aims to achieve.

"Ultimately, as the text of the protocol explains, ‘the judge will try to generate a spirit of co-operation between the court and the advocates on all sides'.

"The expeditious conduct of the trial and a focussing on the real issues must be in the interests of all parties.

"I sincerely hope that these new measures will be received in a similar spirit, and that their implementation will encourage commitment and creativity in lengthy and complex proceedings in our criminal courts in a fair and efficient manner.”

A report titled 'The Management of Lengthy or Complex Criminal Cases' set out guidance on how the new target can be achieved.

It said the same judge should manage lengthy cases "from cradle to grave" and the prosecution have to provide a written summary of their evidence a week before a preliminary hearing.

The report said that judges must exercise "firm control over the conduct of the trial at all stages" to prevent "scare public resources" being wasted.

It recommends electronic presentation of evidence and a clamp down on questioning which is not relevant to the charges.

The report stated: "A heavy fraud or other complex trial has the potential to lose direction and focus.

"This is undesirable for three reasons: the jury may lose track of the evidence, thereby prejudicing both prosecution and

defence; the burden on the accused, the judge, and indeed all involved may become intolerable and scarce public resources are wasted.

"Recognising that a certain amount of scene-setting may be necessary, experience nevertheless suggests that examination-in-chief is often highly repetitive and lacking in focus.

"The judge can and should raise this if it becomes an issue. Moreover the judge can and should indicate when cross-examination is unduly prolix, irrelevant, unnecessary or time wasting."

McLaren, of Bridge of Weir, Renfrewshire, was jailed for 11 years in May last year over a complex property fraud scheme. His wife Lorraine was sentenced to two and a half years.

Graham Clarke and his wife Lindsay walked free from court over charges of running a £7.5 million cocaine and money laundering operation. The case against the Clarkes, who received more than £330,000 in legal aid, was found not proven at the High Court in Glasgow in April 2016 after a five-month trial.

Former Rangers owner Craig Whyte was cleared of fraud in relation to his takeover of the club last year following a seven week trial which cost more than £1.5 million.

In 2011, nurse Malcolm Webster was convicted of murdering his first wife and tried to kill his second in two staged car crashes following a trial which lasted five months at the High Court in Glasgow.

The Lord Advocate, James Wolffe QC, said the new guidance had been built on "mutual respect" and reflected lessons learned from previous complex prosecutions.