The insurer says the money Ramsay is asking Medibank to pay in renegotiations of a 12-month contract is too high and not a fair reflection of the real cost of care.

But Ramsay has countered Medibank's claims, saying negotiations had stalled because it ''would not be coerced into accepting pricing which could threaten patient quality''.

"Medibank have not passed on sufficient increases to private hospitals for some years," Ramsay's manager of corporate and commercial operations, Paul Fitzmaurice, said.

"To meet the rising costs of wages as well as the ever-increasing costs of healthcare, technology and infrastructure, it is fundamental that health funds pay appropriate rates to private hospitals or the whole value proposition of health insurance would be undermined.''

Medibank Private says if Ramsay refuses to submit a lower figure, its members may incur higher out-of-pocket costs if they attend one of the Ramsay Health Care hospitals.

"We will not simply sign a contract with a hospital at any cost,'' Medibank executive Andrew Wilson said.

''Each year our payments to hospitals grow by more than our premiums increase. In the last 10 years our hospital payments have grown by more than 97 per cent,'' he said.

Medibank has written to 9,000 doctors working at Ramsay clinics in Australia to express its ''disappointment'' over the matter.

The contract in dispute relates to the ''unit cost'' that patients are charged when they stay a night in hospital, and it rises depending on the cost of treatment.

The current contract is due to expire at the end of the month.

''This is a serious situation that needs to be resolved,'' Dr Wilson said.

Ramsay controls 30 per cent of the private beds available in Australia. Last financial year it reported a net profit after tax of $244 million.

Negotiations went public on Tuesday when Medibank - Australia's biggest health insurer - took out advertisements in The Australian and The Australian Financial Review newspapers, claiming it was ''working hard to keep costs down'' as hospital costs rose.

The row comes amid widespread suggestions that Medibank is tightening its belt before an expected listing under a Coalition government.

The insurer denied this was playing a role in delaying negotiations.

''What may or may not happen in 12 months or future time is really speculation,'' Dr Wilson said.

A Medibank spokeswoman said patients could expect to pay 15 per cent of the covered cost of an overnight stay in out-of-pocket expenses if the contract expired.

Carol Bennett, chief executive officer of the Consumers Health Forum of Australia, said the focus of both parties should be to reduce out-of-pocket expenses incurred by consumers.

''Australians are already paying some of the highest out-of-pocket costs,'' she said.

''Whatever the outcome of this dispute, we would want to know that out-of-pocket costs for the consumer are kept to a minimum. It is becoming very difficult for many people to afford private health care.''

Mr Fitzmaurice said Ramsay would be advising patients to ''choose to transfer to another health fund'' if necessary.

"Ramsay Health Care has contracts with all other health funds and patients covered with these health funds are not affected," he said.

Ramsay operates 28 private hospitals in NSW, including St George Private Hospital, North Shore Private Hospital and Westmead Private Hospital.

Ramsay shares fell 6.5 per cent to close at $33.44 on Friday.