London Bridge Hospital could change hands after the Competition Commission ordered the HCA group to sell two of its London private hospitals.
The recommendation that HCA should sell London Bridge Hospital and Princess Grace Hospital comes as part of the Competition Commission's inquiry which found that many private hospitals face little competition in local areas across the UK and that there were high barriers to entry.
"We've looked hard at how we can meet the challenging task of opening up this market to increased competition," said CC chairman Roger Witcomb.
"We're now proposing those measures which we believe will offer practical and effective ways of improving competition and ensuring private patients get a better deal.
"Requiring operators to sell hospitals is a big step and we have focused on those areas where a sale will be effective in increasing competition – where a single operator owns a cluster of hospitals which face little rivalry."
Mike Neeb, CEO and president of HCA International, said: "The Competition Commission's provisional recommendations are plainly wrong. The CC's own report acknowledges there are nearly 50 competitors in Greater London, our ownership of these hospitals encourages competition and drives a higher standard of care among hospitals in the UK."
"13 years ago, we acquired the London Bridge Hospital in a merger specifically approved by the Office of Fair Trading. Since then we've invested millions, transforming it into one of the best providers of quality healthcare in the world and now the Competition Commission is punishing this success.
"The CC has misunderstood the market and is threatening unjustified and unfair remedies. To forcibly divest hospitals from successful healthcare organisations cannot be good for either patients or our economy."
It is unclear what the implications of a forced sale of London Bridge Hospital would be for HCA's plans to create an annexe to the hospital in three floors of The Shard, with 102 new consulting rooms and 11 treatment rooms.
In a letter to Southwark Council planners, London Bridge Hospital chief executive John Reay said: "The hospital is at full capacity and the need for additional medical facilities continues to grow."
He added: "In the past 10 years HCA International has twice won the Queen's Award for Enterprise in International Trade and London Bridge played a large part in this.
"The hospital treats patients from many countries including Kuwait, United Arab Emirates, Qatar, Cyprus, Pakistan and Russia.
"In 2012 these patients brought £17 million worth of revenues into the borough."