The move is expected to lead to a carriage contract for Rapture on Telewest's extensive cable franchises, and would mark the first time Telewest has invested on its own in a national channel.
Rapture, which is aimed at 12-to 20-year-olds, is the brainchild of Kudos Productions, the independent production company, and Rocketscience, the media buyers. It had intended to launch in November, but had been unable to secure carriage on Britain's crowded cable networks.
The channel has received promises of between pounds 1.5m and pounds 2m from United to help fund development costs, but the payment remains dependent on Rapture securing carriage agreements.
United sources confirmed that talks are taking place with the channel's creators and negotiators from Telewest, with a deal possible just after Christmas. United is keen to retain its holding - believed to be about 30 per cent - and has asked the channel's creators to sell some of their own shares to Telewest.
Media analysts view the move as a further sign of Telewest's commitment to develop cable programming in the UK. It is also taking a lead in the negotiations between cable companies and Hollywood studios to secure pay- per-view movie rights for a digital cable service.