A bitter battle between women workers and their council bosses could cost taxpayers in the North-East tens of millions of pounds.

Thousands of low-paid female local authority staff are set for rises to bring them in line with male colleagues - and compensation payments back-dated six years.

The legal challenge will initially leave councils facing multi-million pound pay-outs and then having to find money each year to fund the new pay structures.

But one authority last night revealed how it has averted a compensation claim from its women workers by agreeing an historic deal with unions.

Ninety per cent of GMB and Unison members at Newcastle City Council voted to back a plan to introduce equal pay for equal value among workers on the same salary scale.

The new pay structure, which affects 6,500 members of staff, will be phased in from next month.

But many other councils in the region are being taken to employment tribunals by low-paid women workers who are demanding the same conditions as male counterparts.

Hartlepool Borough Council is expecting to have to pay as much as £5m in compensation and an additional £1.5m a year to maintain the "single status" salaries.

The challenge involves workers such as carers, kitchen staff, cleaners, teaching assistants and school secretaries who are on the same scales as gardeners and refuse collectors but are paid as much as £250 a month less.

Former union representative Eileen Goodenough, who is helping the women pursue their claims, said last night: "Although their basic pay is the same, the men regularly get 40 per cent more guaranteed each week for so-called bonus productivity.

"Women have never been offered such a provision and yet they have achieved productivity times and targets over the years.

"An extra 40 per cent a week to some of these people is thousands each year - that's significant savings to the councils.

"Low-paid women workers are effectively subsidising jobs and services to the tune of millions of pounds.

Tyneside lawyer Stefan Cross, who was instrumental in winning a landmark case for school dinnerladies against the former Cleveland County Council in 1997, has recruited Ms Goodenough to help with his workload.

He is dealing with 365 cases in Middlesbrough, 150 in Redcar and Cleveland, 25 in Darlington, ten in Stockton and one in Hartlepool, but the implications involve thousands of workers in each authority.

Like many councils, Redcar and Cleveland is trying to settle the dispute out of court, and has set aside as much as £6m for compensation to its 4,000-plus women staff.

Coun Glyn Nightingale, cabinet member for resources, said: "The settlement we will reach will be the first of its kind for a unitary authority in the region.

A spokesman for Hartlepool Borough Council said: "Any settlements will not affect next year's council tax rates, but it is an issue for the longer term which we are monitoring closely."