More than 135 companies have expressed an interest in the £600m public-private partnership set to take over NHS Estates' trading arm, following its separation from the organisation's policy and regulatory functions.

Former NHS Estates chief executive Kate Priestley is now heading the new organisation - dubbed 'Inventures' - which will take on the NHS's£400m surplus property portfolio and NHS Estates trading group, which reported a£12.5m turnover in the last financial year.

The interested companies are understood to include major firms involved in NHS private finance initiative schemes.

The announcement signals a further step in the paring down of the NHS Executive and its agencies to concentrate on policy and performance management.

Ms Priestley said the PPP move was driven by the NHS plan requirement to auction the residual estate by next April, and 'a framework review of the agency to look at whether we should withdraw from some of our activities to concentrate on ministers' agenda'. Without private sector investment, the impact of the agency's changed role would be 'unsustainable' and could lead to 70 redundancies, she added.

The move will mean property originally scheduled for sale over the next three to five years being handed over to a private firm or consortium in a block, releasing 'a large chunk' of its value up front.

Ms Priestley confirmed that the health secretary would have a clawback if the property subsequently achieved a higher value.