The Government has pledged a clampdown on people who try to avoid paying magistrates' fines, after a report revealed that £74m had to be written off last year because offenders could not be traced.

Westminster's spending watchdog, the National Audit Office (NAO), found that more than one-third of all fines imposed during 2000-01 were unpaid.

Auditor General Sir John Bourn said most fines were collected, but added: "Apart from the cost, the failure to bring in the remainder could undermine the credibility of financial penalties as a form of punishment."

He warned that ''significant improvements'' were needed in the management of the fine enforcement process.

The NAO report found wide variations in payment rates in different parts of the country.

Courts in the North were above the national average in their collection rates, with significantly fewer fines written off than the average of 19 per cent in the rest of the country.

Cleveland courts wrote off £377,527, representing 11 per cent of the £3,580,818 of fines - but collected 69 per cent of fines, compared with the national figure of 63 per cent.

In Durham, ten per cent, or £514,831 of the £5,310,342 in fines were written off, with a collection rate of 67 per cent.

Northumbria collected only 61 per cent of fines, and wrote off ten per cent, or £960,516, of its £9,550,385 owed - again much better than the national average.

However, in South Durham, at one of five courts visited by the NAO, inspectors found that less than 1.8 per cent of fines were paid in full on the day they were imposed - compared with an average of more than four per cent elsewhere.