A senior MSP has called for a Holyrood probe in to how the police investigates its own officers.

The SNP's Linda Fabiani has formally requested the justice committee look in to international investigations after two officers were cleared of data protection breaches and fraud earlier this month.

Constables Amanda Daly and Andrew Reid, who are former partners, were under investigation for five and a half years before the case against them was dismissed by a sheriff on January 9.

Ms Fabiani fears "a lack of transparency and potential culture of secrecy" within the police is "not always conducive to the fair treatment of individuals".

The investigation of Ms Daly and Mr Reid is believed to have cost the Police around £500,000, including lengthy absences by the two officers, but is just one of dozens of investigations in to data breaches.

Last year it emerged that 43 officers were under investigation for data protection breaches and that six had been off frontline duties for two years as a result.

The Scottish Police Federation has long argued that the force was applying the wrong test to data protection claims.

Chairman Brian Docherty said: "What we should be concerned about are instances where the data is misused and there is little evidence this is the case."

Ms Fabiani dealt with Mr Reid's case because he is a constituent. Sheriff William Totten, speaking at Glasgow Sheriff Court earlier this month, questioned why Mr Reid and Ms Daly were before him.

After granting a defence motion of no case to answer, he said: "Why it was ever felt necessary to bring criminal charges in this case, their conduct may or may not amount to misconduct- this court has assessed if any evidence of criminality existed, I found it did not."

Solicitor Aamer Anwar, on behalf of Mr Reid and Ms Daly, has written to Chief Constable Sir Stephen House describing their prosecution as "tantamount to a witch-hunt".

Mr Anwar said: "There are many other police officers in similar situations who have been or are being subjected to similar prosecutions/investigations for breach of the Data Protection Act."

Mr Anwar's firm regularly represents rank-and-file officers in misconduct and criminal proceedings. He stressed he had no problem with the police pursuing officers who sold or passed on secret information to criminals.

The force has warned that gangsters are ready to corrupt officers and staff to get access to confidential files.

But Mr Anwar, in his letter, claimed the Data Protection Act was being used a "sledgehammer" to go after law-abiding officers.

He said: "Hundreds of thousands of pounds are being wasted in fruitless investigations.

"Surely it would be better to call for an immediate review into the training of serving officers so that they are made aware of what the procedures exist for accessing electronic systems, whilst at the same time allowing you to review any pending prosecutions/investigations of officers.

Mr Anwar said data protection was being used as a "catch-all" offence, a "weapon of last resort" when counter-corruption or professional standards officers were unable to make more serious allegations stick.

The solicitor called on the chief constable to carry out a full review of internal misconduct hearings "if confidence is to be restored".

Mr Anwar has made formal complaints about the way in which Mr Reid and Ms Daly were treated. "The length of time taken to investigate Constables Daly and Reid was an abuse in itself, Mr Anwar said.

The solicitor cited claims that a senior officer had anonymously phoned Crimestoppers with bogus allegations against an officer that was subsequently investigated.

Mr Anwar said: "Within Police Scotland there is a perception that there is no accountability or transparency of the Counter Corruption Unit, in that they are responsible for investigating complaints against themselves.

"It is hardly surprising then that ordinary police officers feel that they are a 'law unto themselves'."

Police Scotland confirmed it had received Mr Anwar's letter but made no further comment.