A "hands-off" clause in England's Health Bill in England will remove the duty on the health secretary to secure the provision of appropriate health services, lawyers have warned.
A legal team working for independent campaign group 38 Degrees claims the bill "significantly reduces democratic accountability for the NHS".
Referring to GP-led clinical commissioning groups (CCGs) and the NHS Commissioning Board, the legal advisers say the responsibility of providing health services will lie with "unelected commissioners who will only be accountable to an unelected national quango."
"The bill will make it impossible for the Secretary of State to direct that certain services are available and difficult for the Secretary of State to step in if these groups deliver poor healthcare to the local community," the lawyers have advised.
They also warn of an increased risk of a "postcode lottery" in the delivery of health services as the government will lack the power to intervene and ensure a consistent level of healthcare services across the country.
In response, a Department of Health (DH) spokesperson said: "We have made clear that the Secretary of State will continue to be responsible – as now – for promoting a comprehensive health service.
"The NHS will always be available to all, free at the point of use and based on need and not the ability to pay. To say otherwise is absolute nonsense.
"We also made clear that modernising the NHS will both safeguard the future of our health service and will deliver a world-class health service that puts patients at the heart of everything it does. The independent NHS Future Forum confirmed there is widespread support for the principles of our plans."
38 Degrees' legal team also warned that the bill would open the NHS up to increased competition and "increase the likelihood" of NHS services "being found by the courts to fall within the scope of UK and EU competition law."
But the DH spokesperson said: "Competition is not, and will not be, used as an end in itself. The bill does not change current UK or EU competition legislation or procurement legislation or the areas to which they apply."