MEMBERS of the Scottish Parliament are doubtful about the claimed savings of the Scottish Executive's privatisation of prisoner escort and court custody duties.

Robert Black, the auditor- general for Scotland, told members of Holyrood's audit committee that the award of the (pounds) 126m contract to private security firm Reliance had been ''proper and robust''.

However, he conceded the estimate by the Scottish Prison Service (SPS), which signed the deal, that it would save (pounds) 20m over the seven-year contract, was not guaranteed.

Mr Black also said it was ''too early'' to say if the contract would achieve the objective of freeing up police and prison staff for other duties.

Reliance, heavily criticised over a spate of accidental releases, escapes and court delays when it began its contract, was the cheapest of three bidders.

The auditor-general re-vealed last month that Reliance was at fault for 12 out of 23 prisoners released in error since it took over from police and SPS staff in the Strathclyde region in April.

Margaret Jamieson, Kilmarnock Labour MSP, ex-pressed ''concern'' that poor information about what resources the SPS and police had previously committed to escort and custody duties meant the (pounds) 20m savings might not be met.

Mr Black conceded this information - provided to Reliance and the two other bidders to help them know ''what they were taking on'' - was limited.

''That's where my concern lies,'' Ms Jamieson replied, saying that how could the savings be known when figures from the police and the prison service were not available to help make comparisons.

Mr Roberts said the SPS had used a ''public sector comparator'' to estimate that continuing to deliver escort and custody duties itself, along with police, would cost (pounds) 20m more than getting Reliance to do the job.