The boss of KLM UK today stressed the vital importance of a new engine testing facility at Norwich airport, warning the firm may be forced to pull out of the city if planners fail to give the green light to the �1.2m plan - putting hundreds of jobs at risk.

Norwich International Airport has submitted revised plans for the new facility on the eastern side of the airport, in Horsham-St-Faith, which features a 10m-high three-sided aluminium structure able to absorb the noise.

The airport is seeking permission to test aircraft at less than 70pc thrust on an unlimited basis between 8am and 8pm Monday to Saturday, and 9am to 8pm on Sunday, with high-powered testing for up to 30 minutes within one hour. It believes it has found the best solution to minimise noise for residents living nearby.

A final decision will be made by Norwich City Council's planning committee. But officers at Broadland District Council, which has been consulted on the plan, believe the economic benefits of the plan outweigh the impact on quality of life for nearby residents.

Broadland councillors meet to discuss the plan today and are being advised to recommend City Hall backs the idea.

But a consultants' report commissioned by near residents has concluded that people living close to the proposed engine-testing facility will have to endure 'unacceptable' levels of noise without a break.

The airport expects to keep KLM UK engineering at the site and safeguard 341 full-time jobs at the company, plus 100 contract jobs and those in the supply chain, with its revised �1.2m plan.

But with City Hall planners recently rejecting plans for a new Asda store on the other side of the city in Hall Road, KLM managing director Paul Chun underscored the value of the new facility to the firm.

He said: 'I can appreciate that there is noise involved, but I think the plan the airport has developed uses the best think in noise reduction terms that you could find.

'If the council does not support it, that means the end of our business and I could see our parent group thinking what would be the point of having a UK business anymore, and they might look to move to Schipol or Paris, which would be a shame from the point of view of the jobs and technology we have here.'

But objectors living 500 metres away from the site asked consultants to assess the project, amid noise pollution fears for people in nearby communities.

MAS Environmental, approached by Gill and Peter Cook, of Quaker Farm, in Spixworth, believes the airport's noise impact analysis needs to consider other factors.

Its report concludes: 'The prolonged periods of noise impact without respite are unacceptable and as presently proposed it is not feasible to reduce the noise to acceptable levels where it could continue for such long periods.'

Mr and Mrs Cook successfully challenged previous plans for an engine-testing facility after a judicial review.

Norwich City Council had originally approved the application in 2010.

Norwich Airport officials have been asked by the city council to respond to MAS Environmental's report.

Broadland is a consultee and in a report to councillors by Phil Courtier, the authority's head of planning, the engine-testing is predicted to have a 'moderate adverse impact' on the quality of life within Spixworth, Horsham St Faith and Old Catton, pending the results of an assessment.

Broadland adds the impact on the quality of life, but not on health, at Quaker Farm is likely to be 'significantly adverse' during periods of high-power testing.

Mr Courtier's report concludes: 'The key issue which must be assessed is whether the economic benefits associated with the engine testing facility outweigh the impact upon the quality of life of nearby residents, notably the residents of Quaker Farm.

'In this case, it is concluded that the ability to undertake engine testing at the airport is a crucial aspect of the airport's commercial interests and it is considered that the opportunity to continue to test engines at the airport is a significant material consideration in this case, which is sufficient to outweigh the impact on the quality of life for the occupiers of Quaker Farm.'

Phil Gadd, Norwich Airport's property and contracts director, said: 'We are, as an airport, confident the planning and noise consultants we've brought in have done a proper job.'