Seven serving police officers in Scotland are under investigation for gross misconduct in connection with a murder inquiry, MSPs have heard.

The officers, who formerly worked for the police Counter-Corruption Unit (CCU) but now work elsewhere in Police Scotland, have been placed on restricted duties.

Police Service of Northern Ireland (PSNI) is carrying out the probe and the officers could face dismissal if gross misconduct is confirmed, Holyrood's Justice Sub-Committee on Policing was told.

The investigation was sparked following a review by the Interception of Communications Commissioner's Office (IOCCO) in response to fears that police had been ''illegally spying on journalists''.

The IOCCO found that Police Scotland breached guidelines on accessing data in a row linked to journalists sources regarding the investigation into the murder of Emma Caldwell in 2005.

The 27-year-old had been working as a prostitute when her body was found in woods near Roberton, South Lanarkshire and the case remains unsolved.

Complaints were lodged by two serving and two retired officers regarding the data breach.

Following the IOCCO ruling, Durham Constabulary was appointed to carry out an independent review and when the allegations of misconduct regarding the seven officers was uncovered, PSNI was asked to investigate these.

Giving evidence to the Holyrood committee, Police Scotland Chief Superintendent Alan Speirs said: "The reality for us is the Durham report became the pivotal report on which the PSNI conduct investigation was founded.

"It very quickly led to an inquiry that currently involves seven officers."

He added: "None of the officers are under suspension ... the officers who are subject to this investigation at this time are subject to a number of duty restrictions."

He said: "These officers previously had a role within the Counter Corruption Unit, their current roles are within a different area of the business."

Chief Supt Speirs said no allegations of criminality arose during the Durham inquiry.

MSPs also heard a further force, Northumbria Constabulary, is carrying out a review of investigations into complaints against CCU staff from 2009 to 2016.

Mr Speirs said there were up to 24 complaints with 96 separate allegations, which are "largely historical" and from officers and ex-officers subject to investigation by the CCU.

He said he hopes the report from Durham Constabulary, PSNI and Northumbria Constabulary will be published by Christmas, with personal information redacted.

Lawyer Aamer Anwar, in behalf of Miss Caldwell's family, said: "There is real anger and shock that Police Scotland should chose to use Parliament to blurt out such information thus compounding the agony of the Caldwell family.

"Emma’s family have always felt a deep sense of betrayal at the hands of the first police inquiry team,. Sadly the CCU always appeared more interested in chasing journalists and law abiding officers rather than those who let Emma’s killer escape justice. 

"However the first priority for Emma’s family remains the new murder inquiry which 12 years on has given them new hope. As for the CCU it has repeatedly been exposed as out of control rogue unit, it must be disbanded and held to account."