Comcast, the US cable giant, may be poised to join the race to buy the US entertainment assets being sold by Vivendi Universal. These include Universal studios, cable channels including Sci-Fi and theme parks.

According to several US press sources, including the Wall Street Journal, Comcast has expressed to Vivendi a "preliminary, but genuine" interest in the auction process.

If Comcast can be persuaded to make a formal offer for all or part of the Vivendi Universal Entertainment (VUE) collection it could dramatically change the shape of the race.

This is currently believed to be led by MGM, which submitted the richest bid, and perhaps Liberty Entertainment or General Electric/NBC. But Vivendi is understood to be unhappy with the value of the offers it has received - MGM's is some $11.5bn - and would welcome more bidders. Vivendi Universal is reported to be considering floating off part of VUE as an increasingly attractive alternative to an outright sale.

Buying all or part of VUE would further transform Comcast, a venerable old operating company that ballooned with the purchase of AT&T's cable operations last year. Five years ago it had a market capitalisation of $21bn, but the company is now valued at $70bn. By adding a major content provider such as Universal it would become a vertically integrated group spanning cable distribution, cable channels and a studio, resembling AOL Time Warner.

Comcast is due to receive some $8bn from the imminent sale of its stake in home shopping channel QVC to Liberty, although this has been provisionally earmarked for reduction of the group's existing debt burden.

The company's coy chief executive John Roberts was the star attraction at Herb Allen's Sun Valley conference of media moguls earlier this month. He has recently used his power to start a process of renegotiating content deals with cable programme suppliers such as Disney and News Corp.

Other rumours have suggested that Comcast may alternatively seek a stake in Cablevision Systems' sports channels, that it could do a joint venture with Fox to secure rights to American football rights from the NFL or even that it could bid for Disney.