NHS patients will get a “much worse deal” if the government’s health service reforms see NHS hospitals free to earn up to half of their income from private work, Labour has warned.

Opening an Opposition day debate on the role of the private sector in the NHS, shadow health secretary Andy Burnham claimed the elected Commons had effectively been “sidelined” by the government from the debate about the future of the NHS and the unelected House of Lords was “carving up England’s NHS through backroom coalition deals”.

Mr Burnham attacked the government’s mandate to press ahead with changes to the NHS outlined in its Health and Social Care Bill, labelling it both “unwanted and unnecessary” and an “affront to democracy”.

He turned his fire on David Cameron, claiming there was a “terrifying gap between the prime minister’s rhetoric on the NHS and what he is doing in reality”.

Mr Burnham claimed the four main promises on the NHS made in opposition had been broken in government, including “no top down re-organisation”.

He said: “We believe there is a role for the private sector in helping the NHS deliver the best possible services to NHS patients.”

But he stressed Labour’s policy was to use the private sector at the margins supporting the public NHS, adding: “In 2009/10, 2.14% of all operations carried out in the NHS were carried out in the independent sector, and spend in the private sector accounted for 7.4% of the total NHS budget.”

The motion outlines a need for agreed limits on private sector involvement in the NHS, and “notes with concern the government’s plans to open up the NHS as a regulated market”.

It adds the government’s “plan for a 49 per cent, private income cap for foundation trusts… signals fundamental departure from established practice in NHS hospitals” and “calls on the government to revise significantly downwards its proposed cap on the level of private income that can be generated by NHS hospitals”.

Mr Burnham argued Labour’s progress on reducing “those long NHS waits”, would be put at risk by “this careless and cavalier policy of simply abandoning the principle of the cap”.

He said: “If a liberal cap is used, indeed the preferred policy I understand was to have no cap, so no limits whatsoever. But even if a generous and liberal cap was introduced, there is a major risk that hospitals under financial pressure will give beds, theatre time, appointments, to private patients, enabling them to jump the queue and giving a much worse deal to NHS patients.”