A £15,000 pay out is being handed to council chiefs to stop them quitting their £70,000 jobs, councillors unanimously decided, behind closed doors.

Independent consultants have discovered that the borough's five executive directors are underpaid by £15,000 to £20,000, compared with neighbouring authorities.

"The survey has shown an absolutely glaring anomaly at the top," said Cllr Tim Sly, deputy leader of Halton's Liberal Democrats, who backed the payment.

"It's not a pay rise, it's a retention payment. The quality of any organisation depends on the quality of leadership at the top."

It would cost far more than £15,000, he said, to replace directors, through national advertising and recruitment consultants.

A job evaluation will be carried out on the authority's 6,000 employees, the appointments committee will recommend at tonight's full council meeting.

"We want to make sure we give the right pay for the job from the chief executive down to the bin man," said Cllr Sly.

"We will make sure it is not at the expense of frontline services."

The £15,000 payments will have to be repaid if any of the executive directors leave before the job evaluation is completed in June, 2006.

Council leader, Cllr Tony McDermott, appointments committee chair, said: "Evidence from the survey shows that our executive directors' salaries fall some way below those of other authorities, and because we want staff to stay with the council it is important we carry out this exercise.

"As we have not carried out a council wide job evaluation for a number of years, an evaluation scheme is being developed and will be applied to all posts."

Cllr David Findon, deputy leader of Halton's Conservatives, said: "I made my sentiments very clear at the meeting. There are no bars on windows or locks on doors.

"People are free to leave.

"I personally feel aggrieved at it. This is a whopping rise. The average person in this borough is not earning £12,000 to £15,000 a year."

The executive directors include Graham Talbot (education and social inclusion), Dick Tregea (environment and development), Alan Hill (resources and corporate services), Diana Terris (social care, housing and health) and Eira Hughes (regeneration and neighbourhood services).

Labour councillors Frank Nyland, Jon Swain and Mike Wharton voted in favour of the payment at the appointments committee.