MOBILE phone equipment group Filtronic plans to make a multi-million pound investment in its County Durham plant, it was revealed last night.

The Newton Aycliffe factory - which is employing record numbers of staff and producing record output - has recruited 40 staff in the past year and plans to take on a dozen more.

The factory produces specialist chips which provide the "roaming" service between networks on mobile telephones.

Earlier this year, it won its biggest contract to date - with RF Micro Devices, one of the world's largest suppliers of modules for mobile phone handsets.

RFMD is now its largest customer and the Newton Aycliffe site has had to increase production volumes to meet demand.

Group chief executive officer John Roulston said that Filtronic had earmarked £15m for capital expenditure this year - of which several million would be invested in Newton Aycliffe to increase capacity - bringing with it about a dozen extra jobs.

He told The Northern Echo: "Our results are much improved on last year.

"We started work on the RFMD contract in May and are now operating three shifts there, seven days a week.

"This is a dramatic change from last year. Last year, we had a demand problem, but this year there is no demand problem. The problem we have is ramping up production to meet demand and produce higher volumes.

"We have increased our workforce by about ten per cent, but we can only recruit so many at a time because of the rate at which we can train them.

"The job in the Newton Aycliffe foundry is very sophisticated, with very high-value products, so our rate of hiring staff is limited by our ability to train them.

"But the response of our workforce in County Durham to the rigour of three-shift working has been excellent.

"What a workforce - I couldn't have a better workforce. They are terrific.

"The whole area is a good area to employ people."

Over the past year, Filtronic has increased staff numbers from 250 to 450.

The company has a 20 per cent share of a market which has seen 750 million mobile phones produced this year, and which is growing by seven per cent each year.

Filtronic said pre-tax profits across the group had risen from £0.9m last year to £5.5m this year, and operating profit was up from £4.8m to £6.8m.

Filtronic took over the former Fujitsu site at Newton Aycliffe five years ago.

As well as Newton Aycliffe and its head office in Shipley, the group has manufacturing sites in East Kilbride and Stewarton, in Scotland, Wolverhampton and Milton Keynes. It also has bases in the US, Finland, China and Australia.