Shadow health secretary Andy Burnham is set to argue today that all new contracts between hospitals and the private sector should be put on hold until next year's general election. He will claim the Coalition has no mandate to press ahead with "far-reaching and forced privatisation" of services, including cancer treatment.
Private companies received more than £10bn of public money last year. Here are four private firms currently working in the NHS.
Part-owned by Sir Richard Branson's Virgin Group in 202. Signed a £500 million five-year contract to run a wide variety of health services in Surrey. Formerly called Assura Medical.
Founded by a group of London-based GPs in 1996. Bought by Care UK in November 2012 in a £48 million deal. Harmoni has grown rapidly turning over more than £100 million in the last financial year.
Became the first private company to take over the management of an NHS hospital when it took over the running of Hinchingbrooke Health Care NHS Trust in Cambridgeshire. Controlled by Circle Holdings.
Ramsay Health Care
An Australian healthcare provider that owns 22 private UK hospitals, including Rowley Hall in Stafford, West Midlands, which is contracted to carry out procedures for NHS patients.