Kenny MacAskill, Scotland's Justice Minister, yesterday reiterated his call for fewer criminals to be sent to prison, despite alarming new figures that revealed that the country is in the grip of a youth crime wave and the number of people who were sent to jail last year was the highest for a decade.

Seven per cent of 18-year-old males in Scotland committed at least one crime last year, according to government statistics. The number of people sent to jail in Scotland reached a ten-year high of 18,200 - an increase of 9 per cent on the previous year.

The figures, published by Scotland's Chief Statistician, also showed that 15 per cent of crimes were committed by individuals who were already on bail for another offence.

And in contrast to the previous two years, more people were sent to jail than given community service orders - which were handed out to 17,400 offenders. The fact that the courts have opted for custody in the majority of cases is embarrassing for Mr MacAskill, who has made it a priority to reduce the prison population through alternative forms of punishment.

Mr MacAskill claimed that the statistics added weight to his argument that custodial sentences were not always the answer. “In the course of a year, many thousands of offenders who are serving short sentences for minor crimes pass through our overcrowded prisons,” he said.

“The serious and dangerous criminals who are rightly locked up are not getting the help they need to help them to tackle the underlying causes of their offending,” he said. “I remain convinced that community penalties can play an increasing part in our progressive penal policy. There is strong evidence to suggest that re-offending levels are much lower for those who carry out community penalties as opposed to short prison sentences.”

Eighty per cent of the jail sentences handed out by Scottish courts last year were for less than six months. Of the 53,550 criminals who passed through the courts between 2006-07, 65 per cent had a previous conviction within the previous decade.

Andrew McLellan, the Chief Inspector of Prisons, said this year that prison overcrowding was making Scotland more dangerous. Dr McLellan said those jailed for six months or less did not receive any rehabilitation and more were likely to re-offend.

There are currently about 8,000 prisoners in Scotland's jails, which were built to house only 6,000 inmates. Mr MacAskill has sanctioned the building of three prisons, although two are to replace existing jails.

Pauline McNeill, Labour's justice spokeswoman, attacked the SNP's justice policy. She said: “Their unwillingness to build new prisons and their lack of investment into tough community sentences means that Scotland's justice system is in severe danger of going backwards.”

The Conservatives accused Mr MacAskill of creating a “soft touch Scotland”, with his demands for fewer people to be jailed. Bill Aitken, the party's justice spokesman, said: “These figures show the extent of criminality in Scotland, but all we get from our Justice Secretary is a call to jail fewer people. He says that prisons are full so they must be emptied. How is that a proper solution?”

Margaret Smith, the Liberal Democrats' justice spokeswoman, claimed that the figures proved that short-term prison sentences were not effective. She said: “We believe that one way of cutting the reoffending rate would be to replace very short-term prison sentences with tougher community sentences.”

The Scottish government has set up an independent Prisons Commission to examine the effectiveness of custody. It is due to report at the end of the month. Britain's jails will also be criticised today as no more than costly bed and breakfast facilities, as it emerged that thousands of prisoners a year reject the chance of early release.More than 37,000 inmates opted out of tagging and other release schemes between 1999 and 2006, Jack Straw, the Justice Minister, said yesterday. He revealed that 42 individuals have been caught attempting to break into prisons in the past five years. The figures add weight to claims that jail has become an attractive option for many inmates.

Gordon Brown recently blocked a pay rise for prisoners after a warning by Glyn Travis, assistant general secretary of the Prison Officers Association, that inmates were reluctant to leave because drugs were now cheaper in jail. A Ministry of Justice spokesman said: “Prison is anything but soft and it is absurd to suggest otherwise.”