SCOTLAND'S largest police force and its governing body will face further potentially embarrassing investigations into its handling of allegations tens of thousands of pounds in public cash was used to look after a senior officer's elderly relative.

Strathclyde Police Authority (SPA) last night confirmed it had now instigated an independent investigation into misconduct allegations facing its chief constable, Stephen House, and claims of a cover-up.

The chief constable of another force will probe the claims Mr House sanctioned a 24-hour watch over the relative of a senior colleague, retired assistant chief constable John Neilson, in an operation now mockingly referred to as "Auntiegate".

However, at a closed-doors, specially convened meeting, the authority's members also agreed an outside chief constable investigate claims Mr Neilson exerted undue influence over a divisional commander in South Ayrshire to carry out the operation.

The inquiries stem from claims made by a serving Strathclyde officer, who has complained Mr Neilson requested and received round-the-clock protection for his wife's aunt, who suffered from Alzheimer's disease. Operation Park Road lasted 12 days, costing £25,000 at a time of tight budgets.

Mr Neilson has denied he has received preferential treatment. Chief executive of the SPA, Keith Mannings, previously discounted the need for an external probe, but members of the body's Complaints and Professional Standards Committee overturned his decision.

The Association of Chief Police Constables in Scotland will now contact non-Strathclyde senior officers, with the investigating chief constable selected on the basis of their force's capabilities, capacity, availability and where there can be no perceptions of conflict of interest.

In another move, the committee agreed to call in the Police Complaints Commissioner for Scotland to investigate whether SPA senior officers attempted to cover-up the complaints made by Sergeant Martin Porter.

It also voted to refer concerns of how police investigated allegations of assault which faced Mr Porter's teenage son to Her Majesty's Inspectorate of Constabulary in Scotland. Although David Porter was acquitted he later committed suicide.

Dr Chris Mason, a member of the body and LibDem councillor in Glasgow, said: "I am glad the authority has acted decisively and that each of the matters we brought to members' attention will now be investigated by the proper authorities."

An SPA spokesman said: "Members agreed an independent investigations officer be appointed to examine this complaint."

A Strathclyde Police spokeswoman added: "The chief constable is content the SPA has agreed with his recommendations that an independent force should review this case."

Mr Porter has previously claimed his complaint about Operation Park Road was not dealt with properly as the senior officer tasked with the internal Strathclyde investigation was also the lead officer in the operation. Although the police investigation found no evidence of misuse of public funds, Mr Porter has claimed relevant witnesses were not interviewed.

In documents passed to The Herald, Mr Porter sets out the perceived shortcomings of the operation to protect the pensioner, who suffered from Alzheimer's disease. She had made a number of calls to police, saying she had been the victim of crime, but these were later found to be fantasies caused by her condition.