Prime minister Tony Blair's speech on public service reform this week threw the MSF union into turmoil as its leader appeared to make a U-turn over the private sector's role in the NHS.

Reiterating that 'vested interests' would have 'no veto on reform', Mr Blair said: 'I will not flinch from decisions and changes to deliver better public services, no matter how much opposition.'

The response from MSF general secretary Roger Lyons sent shockwaves through the union. 'We endorse the prime minister's plan of conditional introduction of private service provision to improve services in the NHS, ' he said.

His remarks come just a month after a conference resolution reiterating MSF's 'opposition to PFI and further declaring its opposition to public-private partnership arrangements'.

One senior MSF source predicted 'a riot' among the membership.