It is thought that Liberty Global could make a bid within days for Virgin Media - Britain's second biggest pay TV company, with almost five million customers.
Liberty Global has pay TV operations around the world and is the largest cable operator in most of its 11 European markets, including Ireland.
In a short statement, Virgin Media said: "Virgin Media confirms that it is in discussions with Liberty Global, a leading international cable company, concerning a possible transaction. Any such transaction would be subject to regulatory and other conditions."
It is the second time that Liberty Global, which is chaired by billionaire media mogul John Malone, has looked at buying Virgin Media, in which Sir Richard Branson still holds a minority stake.
If a bid was successful, it would see Mr Malone, who is a former News Corporation shareholder, become a direct rival of Rupert Murdoch's market leading BSkyB.
Mr Malone had previously built up an 18% stake in Mr Murdoch's News Corporation, before Mr Murdoch swapped it for News Corp's interest in US satellite business DirecTV.
Mr Malone, who has said previously he would like to enter the UK market, surprised the City when he did not bid for a stake in BSkyB when the Murdochs were forced to drop their attempts to gain full control of the satellite giant in the wake of the phone hacking scandal.
It is thought that Liberty, whose European markets span from Austria to Switzerland, would make savings on set-top boxes and other technology across the group as a result of a deal with Virgin Media.
Virgin Media was formed through the merger of NTL, Telewest and Virgin Mobile in 2006 and is listed in New York.