Sentencing row erupts after Scottish prison numbers leap 31% in 10 years

• "Kenny MacAskill's soft touch approach is not deterring criminals" - Richard Baker, Labour

There were 7,835 prisoners in April 2009 according to a National Statistics publication – a rise of 31 per cent since devolution began, and a 6 per cent increase on the year before. The number of women being sent to jail was up 11 per cent to a record 413.

SNP justice secretary Kenny MacAskill said on a visit to HMP Inverness yesterday: "Prison – if necessary for a long time – will always be the right punishment for those involved in serious crime and those who are a danger.

"That is why we are investing 120 million each year in our prison estate including the building of three new prisons.

"But we cannot and will not build even more prisons to fill them with those for whom prison is not the right answer.

"Short sentences are not working, they do nothing to stop offending behaviour, and as the Scottish Parliament's justice committee acknowledges, they 'have limited effect as a deterrent'."

However, the number of young offenders was down 6 per cent to its lowest level in two years to 334, and the number of fine defaulters sent to prison had fallen by 63 per cent to 11, the lowest since devolution began.

The figures came just a day after battle lines were drawn in Holyrood over the future of sentencing in Scotland with a new criminal justice bill being debated by MSPs.

Mr MacAskill wants to include a provision in the bill for courts to have a presumption against sentences of six months or less.

He remains confident that he can get the measure through when it comes to a final vote next year with Liberal Democrat and Green support.

The first stage of the bill has just gone through without opposition but Labour and the Conservatives hope to change it in the second committee stage and final third reading vote.

Yesterday, Mr MacAskill argued that reoffending rates were not being brought down by sending people to prison.

"The fact is that three-quarters of those released from short sentences go on to reoffend within two years of getting out, while in contrast three out of five people sentenced to community punishment do not go on to reoffend," he said.

That view was backed by Sacro (Safeguarding Communities – Reducing Offending), a largely publicly funded charity involved with the resettlement and care of former prisoners.

It said that the number of remand prisoners awaiting trial had risen by 8 per cent in the last year.

A Sacro spokesman said: "The use of short prison sentences is now all but discredited as an effective method of reducing offending and it is encouraging to see a slight fall in the numbers of those being imprisoned for spells of less than six months."

But critics have argued that there is a black hole of up to 60m in Mr MacAskill's plans.

They also fear that criminals, who often previously had community sentences, will not go to jail for serious crimes.

Last night Labour's justice spokesman Richard Baker claimed that the real problem was a failure to renew the prison estate.

He said: "Kenny MacAskill's soft touch approach is not deterring criminals and his management of the prison estate has been woeful. Why was the build of Low Moss prison delayed? Why is he closing Craiginches prison in Aberdeen?

He added: "Mr MacAskill is looking to weaken the criminal justice system and that is not the right approach for dealing with any category of offender."