Jail overcrowding has worsened because too many people are being locked up by magistrates for petty offences, prisons chief Martin Narey said yesterday.

"Lots of people are in prison now who would not have been 10 years ago," he told BBC One's Breakfast with Frost.

"Custody rates for some quite petty offending have quadrupled. Custody rates at the magistrates' courts for men and women convicted of motoring offences are four times higher now than 10 years ago."