It costs an absolute fortune out of my budget every year to do this

Sir John Orr

He told BBC Scotland that the police were still the best placed to investigate complaints.

But he says public criticism of the police investigating themselves means it is time for a review.

In the last year Strathclyde Police had to investigate 500 complaints, which took up 16,000 hours of police time.

In England and Wales an independent agency takes on that work.

Sir John says the Scottish system is time consuming and expensive.

"It costs an absolute fortune out of my budget every year to do this," he said.

"If some other group can do the job as well as I believe we do it, come and take it all away."

The force investigated 500 complaints last year

He also says there should be a root and branch review of all aspects of drug policy, including the effectiveness of anti-drugs agencies.

And he believes that Scotland's eight major forces should be reduced to three - or even one national force.

Sir John has spent five years in the hot seat at Strathclyde.

The father-of-three, who hails from Kilmarnock in Ayrshire, was awarded a knighthood in this year's New Year's Honours list for services to the police.

He will be succeeded by William Rae, the chief constable of Dumfries and Galloway Constabulary.