Health unions and Royal Colleges will hold a summit tonight to discuss the Government's controversial reforms of the NHS.
The British Medical Association (BMA), the Royal College of Nursing (RCN) and the Academy of Medical Royal Colleges (AoMRC) are holding a 6pm meeting over their concerns about the Health and Social Care Bill.
On Tuesday, the AoMRC met to discuss their fears and said progress on dealing with their complaints had been slow.
A draft statement obtained by the Guardian following the meeting said: "The Medical Royal Colleges and Faculties of the AoMRC continue to have significant concerns over a number of aspects of the health bill and are disappointed that more progress has not been made in directly addressing the issues we have raised."
The medical bodies said that "unless the proposals are modified the academy believes that Bill may widen rather than lessen health inequalities and that unnecessary competition will undermine the provision of high quality integrated care to patients.
"The Academy and Medical Royal Colleges are not able to support the Bill as it currently stands.
"The academy is deeply concerned that the upheaval caused by the changes in the Bill will distract the NHS from the huge task of meeting the current financial challenges."
But several Colleges later appeared to distance themselves from the draft statement.
It is understood the Royal College of Surgeons (RCS) refused to sign up to calls for the Bill to be withdrawn.
Some other Colleges are also thought to be discussing their position following talks with ministers.
The AoMRC issued a fresh statement yesterday saying it had had "extensive discussions with ministers about the detail of our concerns" since the meeting and would issue no further statement at present.
Tonight's summit comes as pressure continues to mount on ministers over the Bill, currently going through Parliament.
There have been concerns at the lack of clinical support for the reforms after the BMA, the RCN and the Royal College of Midwives (RCM) announced their outright opposition and called for the Bill to be scrapped.
While the Government has agreed to some concessions, including a bigger role for hospital staff and nurses in making decisions, it has not been able to allay fears over an increased role for private companies in running the NHS.
As well as allowing more private companies to enter the market, NHS hospitals would be allowed to make up to 49% of their money from private patients.
As a result, most NHS trusts would be able to make at least 25 times more from private patients than they do at present, prompting fears of growing waiting lists for NHS patients.
A critical report from MPs on the Health Committee earlier this week said the reforms were hindering the ability of the NHS to make the savings it needs to safeguard its future.
But Prime Minister David Cameron defended the reforms yesterday, saying they would improve the NHS.
On the ground, the infrastructure needed to implement the Bill is being put in place, with enough GPs having come forward to set up new management groups to cover 97% of the country.
Mr Cameron said there were 4,000 extra NHS doctors, 100,000 more patients treated, and in-patient and outpatient waiting times were lower since the coalition came to power in May 2010.
A Department of Health spokesman said: "Many organisations representing thousands of NHS staff support our plans for modernising the health service and are keen to get on with improving care for patients.
"There will always be some people who oppose changes to the status quo in the NHS.
"That is why we asked the Future Forum, an independent group of health service experts, to review our plans and discuss them with NHS staff, patients, health service unions and other professional groups."
He added: "We have listened and we have made changes which have been widely welcomed including by professional bodies.
"But as the Future Forum made clear, this process cannot go on forever.
"Changes are needed and we want the NHS to be able to make them in the interests of patients."