A full-scale inspection is to be held at Scotland's only privately operated prison, which has been dogged by controversy since opening.

Kilmarnock Prison, which cost �130m and is operated by American-owned Premier Prisons, is to come under scrutiny even though it has only been open a matter of months.

Normally prisons inspectors visit jails every three years.

The announcement by the Chief Inspector of Prisons, Clive Fairweather, has been welcomed by the Scottish National Party.

The Scottish Executive has revealed that staff turnover at Kilmarnock is considerably higher than in other Scottish jails.

In its first six months of operation, 45 staff left. By comparison, only 30 left Barlinnie, even though the Glasgow jail has more than twice as many employees.

Local MSP Alex Neil, of the SNP, said that while there had been no official complaints about the way the jail was run, the high staff turnover must affect the regime.

Parliamentary question

Mr Neil said he was astounded by the figure, which came from an answer to a parliamentary question.

"Three times as many staff left Kilmarnock prison than staff in prisons like Balinnie and Peterhead. The people of Ayrshire deserve to know why this is the case," he stated.

"The public needs to know why this private prison has a much bigger problem retaining staff than publicly-run prisons.

"I want to see the executive acting now to clarify what is actually going on and what impact this high turnover is having on the running of Kilmarnock prison .

"The executive should put any plans they have to expand private sector control of the prison service on ice until they clear this whole sorry mess up."

No-one was available for comment at Kilmarnock Prison.

The privately-run prison was expected to prove a model for others to follow but has been the scene of several disturbances and a riot last autumn.

Catalogue of trouble

In the latter incident, inmates took control of an entire wing for two-and-a-half hours. Staff, fearing for their safety, pulled out and locked the 67 men inside.

The F Wing inmates had the run of their dining area, pool tables, TV room and showers.

Police and firefighters ringed the jail while the prisoners were monitored on closed circuit television.

In other incidents, a prisoner needed 50 stitches after a slashing and another man was stabbed following the disappearance of 15 kitchen knives.

The prison facilities include a full size floodlit football pitch, a 5,000-book library and state of the art gym.