The senior doctor leading a review into the Government's health service reforms has warned they could "destroy essential services".
Professor Steve Field is the chairman of the NHS Future Forum - the group set up to examine the changes.
He said that proposals by Health Secretary Andrew Lansley to increase competition within the health service would be "destabilising".
"If you had a free market, that would destroy essential services in very big hospitals but also might destroy the services that need to be provided in small hospitals," he said.
"The risk in going forward (with the Bill) as it is, is (of) destabilising the NHS at a local level. It would lead to some hospitals not being able to continue as they are."