A LEGAL error may force more councils to waive millions of pounds in unpaid parking tickets if motorists appeal against the fines.

Wording on tickets issued by six Scottish councils between 1998 and 2006 could effectively invalidate them, if challenged, in the second error since some local authorities took over parking enforcement from the police.

The Scottish Parking Appeals Service has warned it is likely to agree with a High Court decision in England which ruled that tickets were illegal due to the "date of contravention" being omitted. Campaigners challenged tickets in Barnet, London, as they did not include both that date and the date of issue.

However, the biggest of the six, Glasgow City Council, has stated the fines remain and non-payers will be pursued. The council has accounted for £560,000 in unpaid fines between the affected dates and collected £5.5m in fines last year.

Last week, Edinburgh City Council decided to write off almost £6m worth of unpaid tickets after the High Court ruling. Edinburgh budgeted to recoup only £475,000, similar to Glasgow's £560,000.

Glasgow City Council was unable to provide the total figure of unpaid fines. The council said it was satisfied its notices were watertight, but it has changed the wording after the English decision.

A spokeswoman for Glasgow City Council said: "Glasgow commenced decriminalised enforcement in October 1999. There are no plans to write off any debt."

She added: "The council has amended the parking Penalty Charge Notice in the light of the English ruling on date of contravention, despite the fact that notices were fully compliant with the guidance given in the relevant Department of Transport document.

"We consider the date of contravention' has no particular relevance since the council does not issue notices from camera enforcement and this is therefore the same as date of issue'."

Last year, a separate legal challenge was mounted over fines in council car parks in Aberdeen, Dundee, and Perth and Kinross after new regulations failed to cover off-street car parking.

The Scottish Parking Appeals Service has written to Glasgow, Edinburgh, Dundee, Aberdeen, Perth and Kinross, and South Lanarkshire councils, over the matter. The spokesman added: "The parking adjudicators would consider each case on its merits."

Edinburgh said it moved to pre-empt legal challenges and changed its tickets as soon as it could. Ricky Henderson, transport convener, said: "It will only be a matter of time before authorities are ordered to cancel these tickets."

Aberdeen City Council said it was taking legal advice on the issue. Perth & Kinross Council is aware of the issues and is reviewing its position.

South Lanarkshire Council said its parking tickets have always been "proper and legally binding". Dundee City Council declined to respond to any question.

Campaigner Barrie Segal urged people to campaign to have all fines repaid. He said: "These councils are being incredibly arrogant. This matter has been known to councils for quite some time and unfortunately the Scottish councils seem to be the worst."