GP leaders said the Board should not be allowed to dictate how consortia work, and called for detail now so that GPs could influence decisions.
Speaking exclusively to GP during a visit to a GP consortium in London last week, Mr Lansley said: 'The Bill may set certain parameters but there will be more that the NHS Commissioning Board will have to set out. I think maybe we can be clearer coming out of the listening and engagement what that process looks like.'
Mr Lansley told a group of GPs, nurses and consultants he met at the event that more clarity may be provided in the Health Bill about how consortia will work. But he said he aimed to do this on a more 'bottom-up than top-down' basis.
He said: 'I don't want to re-write and write back into the legalisation everything that has caused PCTs to be more bureaucratic, more top heavy and more costly than they needed to be.'
He said the government was trying to create flexibility with consortia. 'And legislation, if you get it wrong, can make things inflexible,' he said.
But the GPC said if consortia rules were not set out in legislation, the BMA and other organisations would not be able to influence the plans.
GPC deputy chairman Dr Richard Vautrey said: 'Our concern is that individuals within the NHS Commissioning Board would dictate what happens without any ability for consortia, individuals or professional organisations to comment.
'We want to see discussions now about the make up of consortia, their freedoms and what expectation the government and NHS Commissioning Board are likely to have well before we get to the authorisation process.'
Mr Lansley said that the listening exercise had highlighted that consultants and nurse specialists did not want legislation to block their involvement in commissioning.