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The company, which now has more than 10 million customers, said its full year pre-tax profit had reached £935.2m.

However, the rapid growth has hit the quality of customer service, and Vodafone had to rush to open a new call-centre in Birmingham to cope with the demand.

Profit padding

The profit figure looks better than the actual performance of the business, as it is bolstered by a £66.7m gain from selling parts of the company.

Excluding the exceptional income, Vodafone made a profit of £868.5m - a touch below the forecast of analysts, who had expected a profit figure of about £870m.

Vodafone is currently in the middle of a merger with US mobile phone operator AirTouch.

Chief Executive Chris Gent said in a statement: "When completed, our transaction with AirTouch will more than double our potential for growth in both conventional cellular telephony, in which we will be a clear world leader, and in the new services which will mark the arrival of the wireless information age."

Once the merger is complete, the company wants to propose to its investors a four-for-one share split, in a bid to make its shares cheaper for new investors.

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During the coming year, the company expects to invest about £1bn "on tangible fixed assets". About half of the sum will be spent in the UK.

The rest of the money will go to the Netherlands, Australia and Greece "to enhance capacity and improve quality of service".

Vodafone's shares, which firmed ahead of the results, rose 16 pence or 1.3% to close at 12.98 pounds on the London stock exchange.

Ten million customers

Last year, the Vodafone added 4.6 million customers to its books, taking the total number to a record 10.445 million.

The UK continues to be Vodafone's main market, with more than half of the total customer base.

The biggest success was the company's 'Pay As You Talk' service, which now has 1.8 million customers, up from a mere 198,000 a year earlier.

Growing pains

The company admitted that the dramatic take up of mobile phones put the quality of its customer service under strain.

In March, Vodafone rushed a new 500-staff customer call centre in Birmingham into action.

Lord MacLaurin, chairman of Vodafone said: "On occasions in the year UK growth was so rapid that it caused some problems to the company's customers-facing systems, but the professionalism and dedication of the whole team has enabled the group to present record results on all measures."