The chief inspector of prisons has claimed that overcrowded jails are making Scotland a more dangerous place and warned that an additional 26 new prisons would need to be built each year to keep up with current trends.

Dr Andrew McLellan said the prison system is failing inmates, staff and the public.

The inspector highlighted the rise in the number of short-term inmates, who receive little or no rehabilitation if jailed for less than six months. These people are more likely to re-offend, he said.

He told a BBC1 Scotland documentary: "Last night, the prison population of Scotland rose by 1%. One per cent in one night. If we're to have that same rate of growth you would fill a new prison in a fortnight.

"If you were to have that same rate of growth, you would need to build 26 prisons a year just to maintain the growth we have.

"Overcrowded jails means Scotland is less safe. For the sake of us all, we need to make sure overcrowding is defeated."

The prison population hit an all-time high last year, with 7497 people behind bars. This year it has already exceeded the 8000 mark.

Aberdeen, Inverness and Glasgow's Barlinnie prisons are the most overcrowded.

Barlinnie - Scotland's largest jail - is around 50% over its capacity with 1500 inmates, according to Dr McLennan.

He has stressed that building more jails will do "almost nothing" to solve the problem.

Last year Alex Spencer, former head of rehabilitation at the prison service, produced a report warning that Scotland would need seven new prisons by 2030 under current rising projections.

Justice Secretary Kenny MacAskill said yesterday the Scottish Government was seeking to tackle the problem with the setting up of a prisons commission under former First Minister Henry McLeish.

The extension of the home detention curfew means that non-dangerous criminals near the end of their sentence can be let out under supervision, he said, and other options are being looked at to ease overcrowding.

He told BBC Radio Scotland: "When you have people just going in and out of prison in revolving door circumstances it doesn't address the underlying problem. It makes it worse. We have to have prisons not simply to lock up those who are dangerous but to seek to rehabilitate them back into society.

"The prison service in Scotland is excellent but if it is suffering with volume that it can hardly cope with then clearly they cannot address underlying matters."