David Cameron has insisted he is "committed" to the Government's health reforms following what he described as "constructive and helpful" talks with healthcare bodies.

His words followed a turbulent morning for the Government, with the Health Secretary facing an angry protester, and fresh tensions emerging over the reforms. Speaking after a summit in Downing Street, the Prime Minister said: "We had a constructive and helpful meeting, and what's clear is there are quite a few myths that we need to bust about this reform.

"So I'm committed to these changes, committed to taking them through, but we need to do everything we can to explain to people this is about improving and enhancing our NHS, not in any way endangering it."

But the summit itself was mired in controversy after it emerged that opponents of the controversial bill are not attending the meeting. The list of those invited, revealed this afternoon, is: The Royal College of Surgeons, the Royal College of Physicians, National Voices, the NHS Alliance, the Royal College of Paediatrics and Child Health, the Royal College of Anaesthetists, NHS Bassetlaw, the NHS Confederation, ACEVO, Baywide Torbay Clinical Commissioning Group, the Foundation Trust Network, the National Association of Primary Care and the Royal College of Obstetricians and Gynaecologists. Other Royal Colleges, including the Royal College of GPs, were not invited. Labour accused the Prime Minister of closing the door of Number 10 to critics.

Health Secretary Andrew Lansley was also confronted by an angry protester as he walked to the summit. Protester June Hautot, who is a member of the South West London Keep the NHS Public campaign and a former Unison rep, confronted the Health Secretary.

Mr Lansley also faced fresh signs of dissent over the controversial reforms from within the Coalition as a Liberal Democrat ministerial aide broke ranks to call for ministers to reveal the true risks of the new legislation.

Duncan Hames, who is Parliamentary Private Secretary to Energy Secretary Ed Davey, signed an early day motion calling for the publication of a "risk register", which outlines the costs and risks of the Health and Social Care Bill. He signed the motion along with 12 other Liberal Democrat MPs.

Mr Hames told PoliticsHome: "At the time that I first asked the Government about the risk register – nearly three months ago, at Health Questions – the Health Minister stated that they were still considering how to move forward in the timescale the Information Commissioner had given them. I encouraged him to publish the risk register in the knowledge that such documents would normally contain carefully-thought through mitigation strategies that rather than alarm, may actually serve to reassure the public."

The Government has so far refused to reveal the risks in spite of a ruling by the Information Commissioner, but the motion says: "This House expects the Government to respect the ruling by the Information Commissioner and to publish the risk register associated with the Health and Social Care Bill reforms in advance of Report Stage in the House of Lords in order to ensure that it informs that debate."

In total, 75 MPs have signed the motion, which was tabled by Liberal Democrat Andrew George. Today Mr George released a statement saying the Health Bill had "no friends", and that "dignified withdrawal would be best".