Police Scotland has been ordered by a tribunal to pay out £10,000 in damages for "unlawful" spying.

The force was told to make the payment to one of its former officers after a tribunal ruled the force had acted unlawfully when it obtained communications data.

An Investigatory Powers Tribunal (IPT) concluded Police Scotland's actions were contrary to the Human Rights Act of 1998.

Two former police officers and their wives, together with two serving policemen, took the action against the force to "complain of the collateral interference with their privacy".

It comes after Sir Stanley Burton, the Interception of Communications Commissioner, ruled in November 2015 that Police Scotland contravened the acquisition and disclosure of communications data code of practice on five occasions.

The Interception of Communications Commissioner's Office (IOCCO) conducted a review after fears were raised officers had been "illegally spying on journalists", with these incidents linked to the investigation into the murder of prostitute Emma Caldwell in 2005.

Gerard Gallacher, a former police officer who carried out an 18-month journalistic investigation into the case, is to be paid £10,000.

Mr Gallacher told the tribunal he had suffered an "invasion of privacy, familial strife, personal stress and strain and loss of long-standing friendships" as a result of Police Scotland's actions.

The IPT ruled the interference with his rights to freedom of expression were "serious in respect of the obtaining of more than 32 days of communications data".

Of the six complainants, only Mr Gallacher and his wife had been seeking compensation. The tribunal also ordered that an inquiry into the breach of guidelines by police be conducted by a senior officer "from another police force in the United Kingdom other than Scotland, and without any previous relevant connection with Police Scotland".

At the end of July, Phil Gormley, the chief constable of Police Scotland, asked Mike Barton, chief constable of Durham Constabulary, to head an independent investigation into the issue.

Detective inspector David Moran, one of the complainants in the case, welcomed "the judgement of the IPT in connection with their examination of Police Scotland's unlawful actions in trying to ascertain the sources of a journalist" after a newspaper published an article which was critical of the Emma Caldwell murder investigation.

Mr Moran said: "That there is to be an inquiry by an external police force into the circumstances surrounding the affair is a large step forward, however I have concerns that Police Scotland have invited the chief constable of Durham Constabulary to examine the outstanding 'non-criminal' matters only.

"I do not believe that is in the spirit of what was discussed at the IPT hearing on July 22 and that all matters, whether potentially criminal or non-criminal, should be on the agenda for a new independent and impartial enquiry.

"Nobody, including myself, knows the full detail of what happened, the level it reached within Police Scotland and who exactly caused officers to break the laws and codes governing the interception of communications.

"Until that is fully established then, in my opinion, no assumption should be made that criminality was not involved."