NHS 'freezes out' private firms
The NHS has a "closed shop mentality" which stops it working well with private health providers, according to a think tank's report.
Civitas says this means some patients miss out on better services.
It said it had evidence that staff from private firms were barred from training courses and snubbed at meetings.
However, a group representing private providers said relations with the NHS had improved significantly and Civitas was over-playing the issue.
The report analyses the success of some of the healthcare reforms introduced under the previous Labour government.
These include the introduction of systems designed to allow NHS hospitals to "compete" for work with each other and with independent providers.
The idea behind this was that competition would produce better value for money for the taxpayer, with patient choice driving up the quality of services.
The Civitas report claims that hospitals put pressure on primary care trusts to maintain the status quo, and used "predatory pricing"; manipulating budgets to make their bids for work seem more attractive.
Interviews with dozens of executives from the NHS and private health companies, it said, revealed how the "culture" of the "NHS family" resisted any move towards the free market.
One private executive complained that despite being able to offer a more efficient, cost-effective service, the local NHS "created a cartel" and refused to allow its consultants to work at the private clinics.
One NHS manager told Civitas: "I do not believe many people have bought into the idea that the NHS is the organisation that procures healthcare for the public and where that healthcare is delivered should not matter."
James Gubb, who co-wrote the report, said: "The coalition government has put a lot of faith in the power of the market to meet the NHS's unnerving productivity challenge.
"The problem is the coalition isn't addressing the real issues as to why the market currently isn't delivering: the overwhelming power of hospitals and the closed-shop 'we can do it alone because we're the NHS' attitude so prevalent across the organisation."
However, David Worskett, of the NHS Partners Network, which represents private firms working in the health service, said that Civitas had painted too bleak a picture.
He said the kind of conflict detailed by the report did happen widely in the "early days" of the reforms, and was still present in some areas, but the majority of NHS trusts were now co-operating fully and productively with the private sector.
"Of course, it's dangerous to generalise across the entire system, but in significant parts, independent sector providers and treatment centres are now welcomed."
A Department of Health spokesman said: "This report outlines how competition can greatly improve patient care.
"Our proposals include greater choice for patients over their care and treatment with any healthcare provider who can meet NHS quality and prices. Our plans also include an economic regulator to promote competition and ensure it works in the interest of patients and the taxpayer."
The report comes as the NHS is gearing up for a further bout of controversy on the role of private contractors.
Doctor's union the British Medical Association has been critical of fresh changes aimed at devolving power and budgets to GPs.
Last week, it said while it did not oppose the plans in principle, it had concerns about the speed of change and the increasing commercialisation.
Under the reforms, GPs would be able commission services for patients either from the established NHS or independent providers.