The SPS said scrapping some custodial sentences could help

The SPS said short-term sentences were ineffective, costly and contributed to an overall prison population of 7,000.

In a submission to the Scottish Executive, the SPS said community sentences should be used more often.

It said capping the number of prisoners could be introduced to "focus on reducing prison numbers".

The executive's consultation ends on 16 July.

Many prison personnel will express the view that short term imprisonment is counter-productive SPS submission

The SPS said: "The levels of imprisonment requires to be addressed and focus is needed on reducing numbers in prison - particularly remand and short-term prisoners.

"Perhaps the Sentencing Commission will propose that custodial sentences under one year should be abolished - something with which the SPS would concur.

"Generally speaking, community-based disposals are more effective than imprisonment at these sentence lengths."

The SPS said a short prison sentence could expose people to more serious criminals, cost someone their tenancy or job, damage their family life, impact on their health and lead them into drugs.

'Prison numbers rising'

"It is for these reasons many prison personnel will express the view that short term imprisonment is counter-productive and does not represent value for money to the taxpayer," the SPS said.

The SPS warned that the executive's plans to build two new prisons would cost �500m over the next 25 years.

Instead, it said community sentences offered a cheaper alternative.

It said: "At a time when crime is on the decrease, the SPS is unsure as to why prison numbers are rising.

Annabel Goldie said Spain and Ireland led the way on prison policy

"We could also consider capping numbers and introduce a queuing system as used in some other European jurisdictions.

"Electronic monitoring (tagging) is also an option to reduce prison numbers while retaining an element of control in the community."

An SPS spokeswoman said the cap would be on the overall figure but someone convicted of murder would still automatically go to jail.

"This idea is about bringing in some allowance for someone not deemed a danger to the public but who will have to serve a custodial sentence," she said.

Learning lessons

The Scottish Conservatives said the debate on prison numbers had become "muddled".

Tory justice spokeswoman Annabel Goldie said Scotland had a low prison population compared with recorded crimes.

She said: "We should be taking lessons from Ireland and Spain.

"Spain imprisons four times more people than Scotland relative to recorded crime, and Ireland three times more.