In some parts of the country the process is taking as much as seven months, according to a report by the Audit Commission.
Local authorities are failing to introduce schemes to prevent re-offending while more than pounds 70m is being wasted in the course of processing young criminals.
The study by the spending watchdog suggests Labour has much to do if it is to meet its election promise of tackling long delays in dealing with persistent young offenders aged 10 to 17.
The Home Office has about three years to meet its 71-day target for dealing with a young offender from the point of arrest to sentencing.
A survey of 120 local authorities during 1997 found it took, on average, 131 days to process offenders in youth courts. "Such a long delay means that a young person caught for breaking into a car, say, at the end of February, does not know his punishment until midsummer," says the report.
"It can be difficult for a teenager to make the link between cause and effect over such a long period."Reuse content