More than 600 jobs could be coming to the county– but only if a controversial business park is given the go-ahead.

Two large firms are backing a planning bid for a manufacturing, warehousing and distribution complex off Junction 8 of the M20, the Leeds Castle turn off.

Automotive Distributors Ltd (ADL), a fast-growing auto parts specialist, and Scarab, manufacturer of road sweepers sold worldwide, want to move their operations from Marden to the proposed 38-acre site. Both say it would enable them to design their new plants from scratch, make them more efficient, reduce costs and cut lorry movements around Marden.

ADL is part of the German Bilstein Group and employs 230 people. It is already in the process of recruiting 50 new people to cope with annual 20% growth and will need another 100 by 2016, boosting its potential workforce at Junction 8 to about 375.

“We’re literally bursting at the seams,” said operations director Paul Dodgson.

“We are 95% to capacity,” ADL has identified a possible site in Sittingbourne but it is not ideal and could mean losing staff because of the distance involved. It has to make a final decision by the end of the year.

"We need to retain key staff and minimise risk. We couldn’t get a better location for European markets. It would be awfully sad if a company like ours can’t locate to Maidstone at a time when the economy is in the doldrums.”

ADL has been working closely with Gallagher Group, the developer, on the £20 million project.

If we moved to Junction 8, it would cut our average employee travel time by about 15% to 20%,” Mr Dodgson added.

'We need to retain key staff and minimise risk. We couldn’t get a better location for European markets.'

He promised “no expense would be spared” in making the warehouse and offices blend in with the environment.

Dave Cassingham, managing director of Scarab – a finalist in the 2013 Kent Excellence in Business Awards (KEiBA) for international success – confirmed he was backing the planning bid. The company is prepared to invest up to £15m in the site.

“In principle, I’ve agreed to support the application and I know it’s been designed around our general requirements,” he said.

"That would be a significant advantage to us in terms of our business plan and strategy.”

Scarab, part of the Fayat Group, employs about 220 at Marden where it manufactures the sweepers. Current export growth has seen the staff already increase by 10% in the last year – overseas sales now account for 70% of turnover.

The move coupled with continued success and further expansion could create at least 50 more jobs.

“It’s a prestigious location in addition to being very well located for materials coming in and our vehicles going out. It would save lorry movements around Marden. Overall, it would be an improvement in terms of our staffing location.

“We’ve been increasing our export order book and think that will be sustained for the foreseeable future. However, we may be restricted by our current facilities. Junction 8 might just provide us with the expansion we need and the jobs that would bring.”

He added that Junction 8 was the only suitable alternative site in Kent.

But the project is controversial because the farmland site has not yet been formally designated for business use. Some local residents have raised objections, already bruised by the eventually successful campaign to thwart the KIG – Kent International Gateway – warehousing project.

However, Gallagher says the proposed development would be only one sixth the size of KIG, high-quality, well screened and sunk in the ground so that little of the warehousing would be visible. It would be built to the highest environmental standards, and offer local people high quality jobs.

A planning application is expected to be submitted to Maidstone council next month