A motion backed strongly at the BMA's ARM called for strict limits on private involvement.
Firms should be brought in only if NHS providers cannot deliver a service, and if it can be guaranteed that this will not damage existing services, it said.
Contracts with private providers should be short-term stop-gaps until NHS providers can take over, and private firms should not be allowed to withhold information on the grounds that it is commercially sensitive.
They should also be obliged to provide medical training, education, research and development to the same level as NHS trusts.
GPC member Dr George Rae said it was vital for the BMA to oppose the DoH as it 'ploughed relentlessly on with a market-orientated ideology'.
'Any expansion of the private sector role in providing care should be dependent on meeting need - a need identified by the NHS for services the NHS cannot provide itself,' Dr Rae said.
Doctors also backed a motion calling on the DoH to stop allowing private providers better contracts than NHS providers.
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