Alan Johnson, the health secretary, yesterday slashed a long-planned expansion of the private sector's role in the National Health Service, in effect confirming that contracts originally meant to be worth about £6bn for surgical treatments and diagnostic services are likely to amount to well under half that sum.

The health secretary announced that three small contracts for scans and renal dialysis, worth £40m a year, would go ahead. But six more surgical treatment centre contracts have been scrapped, taking to 15 the total abandoned since the procurement was launched in 2004. Only one out of nine original contracts for diagnostic services now survives.