The Local Government Ombudsman, giving its provisional view on a complaint about the authority, also said that by not finalising some papers before a meeting, the council had left itself open to allegations of intentionally withholding information from the public.
It has also recommended that the council should finalise background papers before public meetings and make them available for inspection before such meetings in accordance with regulations, and that the council should provide training to relevant staff to ensure they are fully aware of the requirements of regulations.
The complaint was made by local economic development adviser Gwen Swinburn, who on May 14 last year asked to see a report which she considered was a background paper to the Local Plan preferred options.
The Ombudsman said the council told her it was not yet able to share the report but all the supporting documents and studies would be made available on June 5, when the public consultation on the Plan would start.
"It explained that it was finalising and checking some of the studies to ensure the information was organised and presented in a co-ordinated and coherent way," said the Ombudsman. "The report was then made available on June 5."
Th Ombudsman said Ms Swinburn claimed that when the background papers were made available in June, it was clear from the dates that some of them had been finalised before April and the council failed to comply with regulation requirements by not making all the background papers available before a cabinet meeting on April 30.
"I consider that, on the balance of probabilities, at least one of the background documents had been finalised before the Cabinet meeting on April 30 and therefore should have been made available for inspection by members of the public," it said.
"This was administrative fault. I will reconsider this view if the council is able to provide evidence to show that each of the background documents had not been finalised before April 30."
Ms Swinburn said she had complained to the Ombudsman because she believed there was a growing disregard for democracy at the authority and she was pleased by the provisional view.
Council director Darren Richardson said: “We are looking at the Ombudsman’s provisional comments and will be preparing a response to this soon. Until this has been carried out, we’re unable to add any further comment at this stage.”