All of the firms have experience running surgery centres elsewhere

BBC News Online examines who these firms are.

Anglo Canadian Clinics will run three diagnostic and treatment centres in London.

It is a consortium of companies from both Britain and Canada.

These include Calgary Health Region and the University of Calgary Medical Group, both public health providers in western Canada; and Surgical Centres Inc, which runs private surgery clinics in Alberta and British Columbia.

The British members include Accommodata Ltd, a housing provider; Bowmer & Kirkland, a construction company; and Torex Medical Systems, which specialises in computer applications for the health sector.

Birkdale Clinic will run one diagnostic and treatment centre at Daventry.

The company was set up in 1992 as a private ophthalmic clinic. It now has four private hospitals in Liverpool, Rotherham, Preston and Daventry.

They provide orthopaedics, general surgery, refractory eye surgery and cosmetic surgery.

Care UK Afrox is a partnership between Care UK, which operates nursing and residential homes in the UK, and Afrox Healthcare Ltd, which is owned by BOC.

Afrox Hospitals owns and manages 60 private acute hospitals in South Africa and same day surgery clinics.

It has over 12,600 employees, runs a nursing college and provides occupational health services to a range of companies.

Mercury Health is part of the Tribal Group, which provides consultancy and professional support services to the public and private sector in Britain.

It also includes a number of other companies, such as Ascent Health, formerly Johnson & Johnson manufacture of healthcare products, and recruitment specialists Reed Health Group.

Nations Healthcare is an international consortium of British, American and Australian companies.

It has been selected to run two clinics in two centres in Bradford and Burton.

The consortium includes Same Day Surgery, a major outpatient surgery provider in Chicago; MIA Lodestone, a British-based provider of diagnostic services; Vision Group, an Australian provider of specialised eye care; Johns Hopkins International, part of Johns Hopkins Hospital in Maryland; and Harvard School of Public Health.

Netcare UK, which is based in South Africa, will run one diagnostic and treatment centre in Manchester and two mobile ophthalmology clinics.

The group owns 45 private hospitals and 61 specialised medical units in South Africa. It also manages hospitals in the Middle East.

New York Presbyterian is a major university hospital in the United States.

It has two medical centres - Columbia Presbyterian Medical Center and New York Weill Cornell Medical Center.