Natural England and the RSPB now believe the proposed 'energy from waste' plant at Saddlebow will not pose a threat to sensitive sites such as The Wash and Roydon Common.

Their change of heart over the controversial scheme comes days after the Envrionment Agency said it no longer feared the plant would be at risk from flooding.

Their submissions are among more than 3,000 responses received during a second round of consultation over Cory Wheelabrator's planning application to build the incinerator at Saddlebow.

Developers were asked to provide further information about the incinerator's possible impacts on the environment.

Government conservation watchdog Natural England had originally warned that based on information made available, the proposals were likely to have a significant effect on Roydon Common and Dersingham Bog Special Area of Conservation due to acid deposition.

But in its submission to Norfolk County Council's planning consultation, published online today, it said: 'Taking account of the additional information supplied to Natural England, our final advice is that this proposal is not likely to have a significant effect on Roydon Common and Dersingham Bog SAC and Ramsar Sites.'

Natural England had also questioned whether emissions from the plant could cause toxins to build up in shellfish in The Wash.

'These are an important component of the designated intertidal mudflats and sandflats feature, which also supports internationally important populations of overwintering birds,' its submission says.

'It is our view that the further information provided indicates that there is likely to be no significant long term impact on invertebrate populations within the subject site.

'It is our opinion therefore that the conservation objectives for The Wash and North Norfolk Coast SAC and The Wash SPA, Ramsar Site and SSSI to maintain site features in favourable condition would not be adversely affected by the proposed development.'

Also today, it emerged that the RSPB had abandoned its objections to the incinerator. It said that new information it had received had addressed its concerns.

But it added: 'We recommend that should permission be granted, that it be accompanied by a condition to secure continued monitoring of The Wash for the period of the development.'

John Boldon from Cory Wheelabrator said: 'It is excellent news that Natural England has followed the Environment Agency in withdrawing its concerns over the project.

'This means that significant progress has been made in gaining support for the Willows Power and Recycling Centre proposals from key statutory bodies.'

Campaigner Mike Knights said: 'Over recent months there have been big clues government bodies like the Environment Agency and Natural England would let us down.

'Once the Environment Agency obediently withdrew their objection we did not feel confident Natural England would hold out much longer. This proposal has much more to do with big money and vested interests than offering a responsible waste treatment.'