Conservation groups are trying to block the planned demolition of one of Scotland's most notorious jail blocks.

The authorities will find out on Wednesday whether their application to knock down C Hall at Perth prison has been successful.

Historic Scotland said the hall, which dates from the 19th century, is architecturally important and should be preserved.

Perth and Kinross development control committee will decide the hall's fate.

Clive Fairweather: Restructuring "long overdue"

C Hall is part of the original Perth prison built to house thousands of French prisoners from the Napoleonic War.

It is recognised as one of the most outdated in Scotland and one of the few blocks left in the country where the practice of "slopping out" still takes place.

But the proposal to tear down the A-listed building and replace it with a modern facility has brought strong objections.

Historic Scotland said it was not convinced the case for demolition was justified and the Architectural Heritage Society of Scotland branded the plans "preposterous".

'Needs must'

The Scottish Prison Service (SPS) however, described the hall as the worst in the jail and said it should be replaced.

A spokesman said: "It is widely recognised that the practice of slopping out is unacceptable and this demolition is really a case of 'needs must'.

"C Hall is a listed building. However, we are confident that our reasons for its demolition and rebuilding are sound and it is up to the local authority now."

Prison inspectors last May praised improved conditions at the prison which, they said, had "suffered many years of neglect".

A report by Clive Fairweather, the then HM Chief Inspector of Prisons, praised investment at the jail.

There was unrest at the jail last year

But he criticised the conditions experienced by short-term prisoners housed in C Hall.

The report said conditions in the block were "unacceptable".

Mr Fairweather said at the time: "Its old gallery structure, and in-cell electrical power, indicate that fundamental restructuring is long overdue."

An SPS investigation was launched last June after a disturbance at the prison that month involving about 40 prisoners.

The fire brigade was called to deal with a fire which was thought to have started during the unrest.

The inmates had refused to return to their cells in the C Hall block, but the situation was brought under control an hour later.