But, with the average daily population at Perth Prison increasing from 443 to 655, breaches of discipline per head actually fell from 4.08 to 3.77 over this period.

The figures show that levels of assaults had risen from 56 in 1999/2000 to 110 in 2004/05, and the number of incidents of fighting increased from 45 to 79 over the same period.

The figures for those disobeying a lawful order also saw a sharp rise, from 583 in 1999/2000 to 1119 in 2004/05, and those who disobeyed a rule or regulation doubled from 58 to 120 in this period.

However, the statistics are not all negative, with 95 prisoners intentionally endangering the health or personal safety of others in 1999/2000 decreasing to 59 in 2004/05, and incidents of arson falling from 13 to 2.

Inmates used threatening, abusive, insulting, indecent or obscene words or behaviour, fell from 123 in 1999/2000 to 94 in 2004/05.

Deputy governor Martyn Bettel today said he wasn’t surprised by the figures, which were collated by the Scottish Prison Service (SPS).

He said, “Order within Perth Prison is generally good, especially for the high prisoner number and mix and type of prisoner, although there have been relatively high levels of prisoner-on- prisoner violence.

“Actions to address order issues and review incidents have been introduced, such as post-assault and incident interviews and debriefs, intelligence analysis, data analysis and the introduction of an anti-bullying strategy.”

He continued, “Considering we have a high proportion of young offenders, who come in here off the street, the levels of violence are minimal.

“You would think the statistics would be higher considering many of these people may have grudges to bear when they are first admitted.

“There are some incidents — it wouldn’t be normal if there were not — but most of it isn’t that serious.”

Mr Bettel believes the three-phased revamp of the prison currently under way — which will see a £17 million laundry and energy centre unveiled next month — will substantially alter perceptions of the building.

He said, “Until June 2005, Perth Prison had the dubious distinction of occupying the least suitable prisoner accommodation left in Britain.

“The investment now under way will make a decisive contribution to the establishment being fit-for-purpose in the context of modern Scotland, as well as providing more spaces and enabling long-term operating efficiencies.

“With its broad mix of prisoner groups and existing community agency relationships, it is well placed to face outward with the advent of the Community Justice Agencies, and to play a positive role in meeting the objectives of the Scottish justice system.

A spokesman for the SPS said the explanation for assaults may be neighbourhood rivalry.

“Previously, people on remand from the south of Fife were kept at Edinburgh Prison. But, two years ago, this was changed and they were transferred to Perth,” he said. “People can get territorial and this may be a reason for the increase in assaults, particularly if they are young.

“But, since C Hall was closed, things have improved. The archaic practice of slopping out ended and I would say there has been a number of years since there was a large-scale incident at Perth Prison, and that is due to it being well-run by the management.”

Perth Prison holds adult male prisoners serving sentences of less than four years and those remanded from the courts in Perth, Dundee, Angus and Fife.

The prison also accommodates long-term adult male prisoners in secure conditions, including high supervision prisoners, who are serving sentences up to and including life imprisonment.