Virgin Media formally hoisted the “for sale” sign last night, revealing that it is considering a $23 billion (£11.5 billion) offer from Carlyle, the US buyout group.

The confirmation of an approach came as it emerged that other buyout firms are considering joining forces to mount a rival offer. Apax and Providence are believed to be potential contenders, although Apax is also known to have held talks with Carlyle about joining its bid. Blackstone and Cinven are thought to be weighing up whether to join the fray.

Hopes of a bidding war for the communications group sent its Nasdaq-listed shares surging 15 per cent in early trading in New York yesterday.

City sources said that Carlyle had approached Jim Mooney, the Virgin Media chairman, several weeks ago with an offer of $33-$34 a share. The offer represents a premium of more than 35 per cent to the cable group’s Friday closing price of $24.37 and gives it an enterprise value of £11.5 billion. The group has £6 billion of debt.

Carlyle declined to comment last night. However, City sources said that its plans for the cable group included an eventual relisting of the new entity in Britain.

Carlyle is also thought likely to focus on content and the development of its Flextech business. It is thought likely to introduce new management to replace Steve Burch, the group’s chief executive. It is also expected to seek to settle the long-running row with BSkyB, which is 39.1 per cent owned by News International, parent company of The Times.

In its statement, Virgin Media said that it had received an approach that was contingent on conditions, including a period of exclusivity. Sir Richard Branson, the group’s biggest shareholder, with 10.5 per cent, is understood to be supportive of the approach.

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