AN online betting firm says it expects to continue its growth after attracting new customers and expanding across the US.

Betfair, which is the world's largest internet betting exchange, says half-year underlying profits before tax have risen 56 per cent to £32m, with earnings before tax expected to reach up to £87m.

Bosses say its Sportsbook venture, which allows punters commission free fixed odds prices and cash back offers on various sports, continues to trade well, with 32 per cent of UK and Irish customers joining through the function in the first-half of the year.

The company said 38 per cent of betting customers also used its exchanges in the first-half of the year, which allow people to lock in profits or losses before a match or event has finished and cash out their returns.

It added revenues from mobile phones was us 70 per cent, with strong revenues in its US division, helped by the launch of an online casino in New Jersey.

Betfair is a key sponsor of high-profile sports action, including the most recent World Snooker Championship, in Sheffield, which was won by Ronnie O'Sullivan, and has signed a deal with the British Horse Racing Association to commit £40m to the sport in the next five years.

It has also secured the rights for advertising packages on Channel 4 Racing's live broadcasts and Morning Line analysis show from 2014.

Breon Corcoran, Betfair chief executive, said: “We have continued to make progress and delivered a good first half performance.

“In the last year, the number of new customers in the UK and Ireland is up 77 per cent and we are continuing to see our Exchange and Sportsbook products complimenting each other, with 38 per cent of customers using both products.

“After cost cuts in the last 12 months, we now operate as a leaner and fitter business, which means we can re-invest to generate revenue growth.

“Our sales and marketing budget is more than £100m this year, and that enables a presence on Sky Sports and an exciting partnership with Channel 4 Racing.

“We are also investing internationally, our online casino launched in New Jersey and we have made good progress towards launching an exchange in Italy.”