Orange has shrugged aside worries about a slowdown in the mobile phone market to ring up an increase in subscriber numbers and revenue.

The group added 284,000 new customers in the UK in the first three months of the year, a 38 per cent rise on the previous quarter.

Darlington's largest employer, with more than 2,500 staff and more than 6,000 employees at other operations in the region, said it was beginning to see the amount of money spent by each of its UK subscribers rise.

The key average annual revenue per user measure edged up in the UK for the first time in the first quarter, to £247 from £246 in the final three months of last year.

The growth was reflected by Orange's operations worldwide as the company took its total customer base to 40.5 million by adding 1.27 million subscribers.

Total turnover across the business in the quarter rose 16 per cent to £2.48bn.

Ian Parker, Orange's director of customer relations, responsible for its call centres in the North-East, said: "These results keep us on track. Customer numbers are continuing to rise, all be it not at the same levels we had previously seen.

"There are still people coming into the market, but the most encouraging statistic is the number of customers switching to Orange from other networks, showing that we are regarded as a quality service."

Orange now has an active customer base of 12.7 million people in the UK, 15 per cent above the figure recorded at the same stage last year.

It is the UK's leading mobile operator with a market share of 28 per cent.

Mr Parker said the growth of non-voice services was particularly pleasing, with text messaging contributing 13.6 per cent of UK revenues.

He said Orange expected average usage and revenue to grow further as new services and handsets were launched.

Orange's rival, Vodafone, disappointed the City last week with a sharp fall in subscriber growth in the first three months of the year. It added 22,000 new customers in the UK and 1.3 million worldwide as its customer base swelled to 101.1 million.

Mobile phone firms have been focusing more on generating value from existing customers than searching for subscriber growth.

Orange, majority owned by France Telecom, added 454,000 customers in France, taking its total to 18.3 million and was signing up 7,000 a day in Thailand, where it launched in March.

Despite the subscriber growth, Mr Parker said Orange still had some way to go before it could claim to be a truly global brand.

"Orange currently operates in around 20 countries and is moving into more every year. We have aspirations to be a truly global brand and the world's leading mobile phone company, but we are a long way from that yet.