Major doubt has been thrown on the future of a scheme to extend Helston's Bulwark Estate following a formal objection from the Ministry of Defence.

Coastline Housing is behind the project to build 75 affordable homes on land next to Nansloe Academy, which has proved controversial with existing residents of that area due to the planned access road directly past the primary school.

The plans are due to go before Cornwall Council's planning committee later this month, but are now in serious jeopardy following the response from the MoD, which runs the neighbouring RNAS Culdrose naval base, approximately 660 metres away.

The council has received a letter from the office of the Secretary of State for Defence, written on behalf of the MoD, objecting on three main points.

The letter states: "RNAS Culdrose is a frontline, operational air station and is the largest helicopter base in Europe.

"In view of the nature of operational and training activity undertaken at RNAS Culdrose, and its close proximity to the application site, the MOD has significant concerns regarding the proposed development and its appropriateness for the application site.

"These concerns revolve around the issues of the potential noise levels that would be experienced by the future occupants of the proposed dwellings, vibration and public safety."

Going into more detail, the Secretary of State stresses that flying at Culdrose took place in order to meet specific operational and training requirements for defence.

With regards to noise, helicopter rotors turned for "extended periods" before and after landing, with the aircraft also hovering the ground for 30 minutes or more during training, resulting in "a distinct dominant tone, which can be particularly disturbing" and it was feared "would likely result in noise disturbance of some description."

The MoD welcomed an environment noise assessment being submitted by Coastline, but it felt that "insufficient data" had been collected.

The letter adds that there had already been cases where private companies had developed areas around airfields, bringing in non MoD residents, which had already resulted in compensation having to be given to inhabitants.

"Therefore any further development in these areas should, unless a specific need has been identified, be prevented," it states, adding that if the council decided to grant planning permission, the MoD would "bear no responsibility for any complaints or claims from new residents in respect of matters of noise and vibration" and would refer them on to the authority.

Similarly, the MoD has concerns that the new homes would suffer from vibrations in floors, walls and windows due to the close helicopter activity, and in turn objects within the house.

Finally, with regards to public safety, the letter states that while there were strict flying regulations and standards it was "not without risk" and it was "suggested that the occupants of the proposed dwellings will be at a greater risk of incursion in the event of an aircraft emergency" such as a bird strike or mechanical fault, compared to the current agricultural use on the land.

While the MoD said it supported the "basic principle of new residential development" in the area, it asked Cornwall Council to refuse planning permission on this specific scheme.

Cornwall councillor for the area, Andrew Wallis, has written on his blog that following a meeting with a planning officer "it is clear if the objections from the MoD are not removed, this application will be refused."