Ministers have announced extra funding for more police

Professor Arthur Midwinter told MSPs that insufficient cash was being allocated to fund recruitment as well as meet existing police pensions.

He criticised the previous Labour/Lib Dem administration for spending less than the UK average on policing.

Scottish police forces will receive an extra £54m to help with recruitment.

Prof Midwinter, who has been advising Labour on the budget, told Holyrood's justice committee that the funding could not pay for both 500 new officers and the rising cost of meeting pension demands.

'Recruiting delay'

He said the important figure for MSPs in terms of extra cash for policing in the annual budget was £22.5m in 2010-11, the final year of the spending review.

This would cover the £15m needed to recruit 500 new officers, but he said it was unclear if this cash was for the expected rise in pension costs, claiming it could not cover both.

"If the £22.5m is the total growth in the police budget, it will put chief constables under pressure to manage their budgets within those figures," he said.

"It will probably lead to a situation, where in classic fashion, they delay recruiting officers in order to make the budget add up."

Prof Midwinter, who also advises the Scottish Police Federation, compiled a recent report for the body which indicated that the force in Scotland was underfunded compared with England and Wales.