Virgin Mobile was launched in 1999

Reporting its results for the half year to 30 September, it said turnover rose by 18% to �256.7m ($478m) compared with �218m for the same period last year.

However, pre-tax profit fell to �30m against �39m a year ago.

The firm, which listed on the London stock market in the summer, said second-half profits would fall further due to the rising cost of boosting customers.

Shares in Sir Richard Branson's firm, the UK's fifth-largest mobile phone service provider, started trading on 21 July, after the original float price was cut by 20%.

The no-frills company was launched in 1999 and uses T-Mobile's network to carry its calls.