A conservation group has accused council chiefs of “cutting corners” in the assessment of a proposed new 165-acre wildlife site to replace internationally-important habitat that will be lost if Sizewell C is built.

Suffolk Coastal council says the scheme for land at Aldhurst Farm at Leiston will be treated separately from any plans for a new nuclear power station and not as compensation as the habitat will be created whether the £14billion twin reactor plant goes ahead or not.

But Suffolk Coastal Friends of the Earth (FoE) says this decision means a less than adequate investigation of the impact of the new site and loss of part of a Site of Special Scientific Interest (SSSI) will take place – with no need for a full Environmental Impact Assessment (EIA).

The group says EDF Energy has openly admitted the connection between the proposed wildlife site off Lovers Lane and Sizewell C as it will “help compensate for potential land-take from Sizewell Marshes SSSI”.

FoE said: “It is notable on the planning portal that the Suffolk Wildlife Trust questions whether the correct appraisals have been done with regard to the vulnerable nature reserve areas. In fact, the necessary assessments are seriously incomplete.

“This leaves our protected habitats and species in and around Sizewell at severe risk.

“Since the reason for this new habitat is to compensate for damage caused by Sizewell C construction works, then that damage must first be formally assessed, in line with the European Habitats Directive.

“This demands that all impacts be included, not just environmental changes caused by the new project itself, but the larger development as a whole, in combination with any other local proposals.

“This has not been achieved and as a result the screening and consideration of likely effects are inevitably misconstrued.”

Rachel Fulcher, the group’s coordinator, added: “These are serious oversights, with a bearing on a massive project that will ravage the Area of Outstanding Natural Beauty and our Heritage Coast.

“Wildlife will be lost and our tranquil, protected countryside will be ruined, along with our tourist trade which depends on it.

“Even if the proper appraisals take one or two more years to complete, then they should be done. Corner cutting like this undermines public confidence.”

In a letter, Philip Ridley, head of planning at Suffolk Coastal, said: “That the proposed habitat creation project is a stand-alone scheme, intended to be implemented and retained regardless of what does or does not happen with the Sizewell C project in due course, has been made clear in the application documents, and in particular in the Planning Statement.”

UK courts had decided that schemes which can go ahead on their own rather than as an integral part of a larger development should be treated as stand-alone and therefore the proposal would not need an EIA.

The scheme will include 14 acres of wetland habitat and a “heathland mosaic” including grassland, heathland, scrub and scattered trees.