A Norfolk council is considering "all possible options" over a biogas site after changes were made from its original planning permission.
Concerns about the construction of an anaerobic digester (AD) - a system that produces fuels from materials like maize and manure - have been waging for months.
The Deal Farm Biogas project, on Kenninghall Road in Bressingham, was originally approved in 2015.
Since then, people have complained that the plans changed without permission – including South Norfolk Council’s (SNC) planning team.
In September, developer BioWatt submitted a variation of condition for the site, which drew overwhelming negativity, with 217 letters of objection against 117 in support. Not all the submissions were local, with some from as far away as Peterborough and Bedford.
In a letter to the developers in October, Tim Barker, SNC planning officer, questioned the legality of the development.
He said: “It appears that the development constructed on site has a number of material differences to the development approved in 2015.
"This brings into question whether the original development was in fact lawfully implemented.
"In addition, part of the current 'development' falls outside the original site boundaries.”
Mr Barker said that development should cease until it has been through a full planning application. The developer says it is working with the council to "agree a suitable approach".
The developer withdrew its application on Thursday.
In a letter to SNC on November 11, Cornerstone, representing Deal Farm Biogas, said it was preparing to do extra work which will take around three weeks and then it will submit a new application.
Despite the questions over the legality of the development, several people told the Local Democracy Reporting Service work appeared to have continued.
One campaigner said: "Work is still going on there.
"Last week they put up masts, they brought in the lorries through different villages."
An SNC spokesperson said: "The applicant has been asked to submit a new application and this new application will be considered on its merits and following full consultation with the community.
“Regarding potential enforcement action, the council continues to consider with its legal advisors all possible options.”
A representative from Storengy UK Ltd, on behalf of Biowatt, said it was working to "conclude work on site as swiftly as possible in a safe and practical manner".
They added: "We are working with SNC and its planning officers to agree a suitable approach for preparing and submitting a revised planning application for Deal Farm, and we will be keeping local residents informed of our next steps."
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