Central Bedfordshire Council made the accusation after the inspectors raised a series of concerns about the plan’s preparation and the authority's approach to the examination process, which they warned raised the likelihood of significant delays before the plan's adoption.
Inspectors Matthew Birkinshaw and Helen Hockenhull wrote to Central Bedfordshire Council on 30 September, outlining issues related to the plan’s sustainability appraisal and strategic allocations.
"The sustainability appraisal has not adequately demonstrated that the spatial distribution of housing and employment is the most appropriate strategy given the reasonable alternatives available," they said adding: "We have serious concerns regarding the soundness of several strategic allocations."
The inspectors also said that participants in the examination hearings had raised "serious concerns" about difficulties in following the process given the amount of post-submission evidence filed by the council and the apparent way in which this "sought to retrospectively justify the plan’s strategy".
Specific concerns raised by the inspectors included the proposed route of a new M1-A6 link road, which would pass through the Chilterns Area of Outstanding Natural Beauty, and a lack of testing of alternative options.
The inspectors referred to post-hearing correspondence received from the Chilterns Conservation Board relating to a resolution agreed by Central Bedfordshire councillors to grant permission for the new link road, subject to referral to the secretary of state.
Responding to the inspectors on 3 October, Andrew Davie, assistant director of development and infrastructure at Central Bedfordshire Council, raised an "immediate concern" about the Chilterns Conservation Board correspondence.
"The council does not have a copy of this communication and it has not been made publicly available," wrote Davie, requesting that any other correspondence in relation to the examination be provided to the authority.
"Only once the council has received, and had time to consider, all the information used to inform your letter, can we seek to respond," he added.
On 10 October, the inspectors agreed to provide two emails related to the link road while also advising that "many emails from various parties" may be received during a local plan examination which are "not routinely copied to the local planning authority and are not normally regarded as examination documents which are published".
However, in a further letter dated 11 October, Davie accused the inspectors of failing to disclose whether any further correspondence had been received.
"Taking into account communications that have not been made publicly available is absolutely not acceptable and is not in the spirit of a public examination which is intended to be open and transparent," he said.
In Central Bedfordshire’s formal response to the inspector’s post-hearing letter, dated 14 October, Davie said: "The tone of the [inspectors’] letter and its lack of clarity does not appear to be consistent with a desire to work proactively with the council to progress this plan, which is not hugely helpful."
Davie said the council intends to appoint an independent consultant to "review and revise" the sustainability appraisal and would provide a series of technical papers addressing the inspectors’ specific concerns about site allocations.
"We expect to complete this work and consultation on the further documentation by April 2020," said Davie. "Following that, and if required, additional hearings can be held from June 2020."
In a statement, Central Bedfordshire Council said it believed "all points of concern can be addressed quickly to secure a sound plan that is compliant with the regulations and fit for purpose".
It added: "Central Bedfordshire Council has committed significant resources to preparing the plan and the communities of the area need to have certainty about where development is to take place. Further lengthy delay is in no-one’s interests and is not consistent with the view from government about the urgency of getting local plans in place as quickly as possible."
A Planning Inspectorate spokesperson said: "We can confirm the council wrote to the inspectors expressing concerns over not having prior sight of some documents referred to in the Inspector’s letter."
"The correspondence has now been shared with the local planning authority and has been made available on the examination website."
This article was updated on 15/10/19 to include the above comment from the Planning Inspectorate.