Government moves to "narrow the justice gap" could see Britain's jail population soar to over 110,000 by the end of the decade.

Forty new jails would have to be built to cope with the extra prisoners.

Home Office forecasters have predicted that an extra 37,000 people could be imprisoned by 2009.

And delivering the required prison capacity could come at the price of two and half pence on the basic rate of income tax.

If targets are met to clear up 1.2 million crimes by 2006 - an extra 185,200 offences - and if current conviction patterns remain the same, Britain's jails will contain between 98,600 and 109,600 prisoners by June 2009.