Officials can now order wheel clamping of defaulters' cars

Warning notices will go up from Monday in courts, followed by newspaper and radio adverts, to collect some of the �354m owed at the end of last year.

Ministers say that bailiffs will visit non-payers in a few days to issue warrants ordering them to go to court.

New measures under Operation Payback will clamp down on non-payers of court penalties and on-the-spot fines.

Fine hikes of up to 50% could also introduced

Defaulters who are unable to pay may be forced to do unpaid community work.

'Payback time'

Courts minister Chris Leslie said the initiative will begin soon but said the exact details would be kept secret so police and bailiffs can surprise non-payers.

He said: "We're giving people a chance to come clean now by warning them through the advertising campaign that they need to pay their outstanding fine immediately, in order to avoid possible arrest.

"If they don't, the next knock on the door could mean payback time has come."

The government is sending a clear message to those who have been fined that payment is not optional and that penalties must be paid Chris Leslie Courts minister

At the end of last year, �354m of financial penalties was outstanding in England and Wales.

The government aims to raise collection rates to at least 75% of criminal penalties by the end of this month.

In March 2003, only 55% of fines imposed were paid on time.

Non-payers will return to court so that appropriate measures to collect the cash, together with additional sums of 25% or 50%, can be set up.

These could include wheel clamping of cars and their possible eventual sale.

Fines can also be deducted from Job Seekers Allowance and Income Support.

Police will identify which warrants to carry out, make sure information is correct and accompany court arrest teams.

John Burbeck, spokesman for the Association of Chief Police Officers, said the operation would "target persistent offenders, reinforce the administration of justice and collect money owed to the courts and compensation owed to victims".

Operation Payback will take place in 34 of the 42 magistrates' court committee areas.