A cross-party group of Norfolk county councillors, led by the UKIP group leader Toby Coke, is to make a further attempt to terminate the Cory Wheelabrator contract while the costs are still capped at £26m, by calling an extraordinary general meeting of the county council in early April.

The group, which includes councillors Tim East (Lib Dem), Andrew Boswell (Green), John Dobson (Con), Alexandra Kemp (Lab) and Richard Bird (Ind) wants an urgent decision from the council on whether to terminate the contract.

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If no decision is taken on planning by Communities Secretary Eric Pickles by May 1, the council will have to decide whether to continue with the contract.

If it does so, the compensation costs are expected to rise by £5m, to £31m.

Mr Coke said: 'It is estimated that the termination costs would increase after May 1 by an eye-watering £400,000 per month or nearly £5 per annum.

'It is absolutely essential that this decision is taken by the full council and not through an exclusive cabinet resolution, nor under powers delegated to the authority.

'The group, which has strong cross-party support, believes that there is no alternative but to seek a termination of the contract, prior to that date.'

Mr East said the group needed five signatures to call the meeting. He added: 'We're demanding an EGM, which we're constitutionally entitled to do. It's a game changern if we get a second bite of the cherry if he [Eric Pickles] hasn't made a decision.'

Norfolk County Council voted by 40 votes to 38 to continue with the incinerator in October. The council gave it planning permission 18 months ago and has signed a contract with Cory Wheelabrator to build and run the plant at Saddlebow, near King's Lynn.

But the planning decision was 'called in' by Mr Pickles, triggering a three-month public inquiry last year.

Mr Pickles was due to announce his decision - arrived at after considering a report filed by the inspector who chaired the inquiry - on January 14.

But officials in his office said the announcement would be delayed. When the EDP asked Mr Pickles when it might be made, he said: 'I'll make it when I'm confident that the decision is a good one.'

Last year, the government withdrew £169m in waste infrastructure credits from the project, saying the burner was no longer needed to meet its target for diverting waste from landfill.

Norfolk County Council faces paying Cory at least £25m in compensation if it terminates the contract. The figure rises by £6m in May.

Pro-incinerator councillors - some who were elected on an anti-incinerator ticket - say it offers the most cost-effective way forward.

But opponents say there are cheaper, more environmentally-friendly ways of disposing of our waste, even taking into account the cost of cancellation.