Virgin Mobile has won more than 4 million customers since 1999

The mobile group said it planned to float its shares before the end of July, subject to market conditions.

Virgin has not said how much of the firm it plans to sell off but the float is expected to value Virgin Mobile at about �1bn ($1.8bn).

Virgin Mobile is the UK's fifth largest mobile operator with 4.1 million customers. It was launched in 1999.

Reports have suggested that up to 40% of the company will be listed.

Raising finance

Many analysts have been expecting the company to come to the market since it gained full control from former partner T-Mobile in January.

I am confident that Virgin Mobile will go from strength to strength Sir Richard Branson

T-Mobile sold its 50% stake in the firm to the Virgin Group to end a long-running legal battle between the two sides.

The money raised by the share sale is expected to be used to help finance other projects for the Virgin Group, including the launch of a low cost airline in the US.

Sir Richard Branson is expected to become the Honorary President at Virgin Mobile.

"In less than five years Virgin Mobile has grown from scratch to acquire more than four million customers, " Sir Richard said.

"I am very proud of what the team has achieved so far and am confident that, following the IPO (flotation), Virgin Mobile will go from strength to strength."