NHS Lothian yesterday rejected demands for it to open its books and reveal details of a multi-million pound deal it has struck to refinance its flagship hospital privately.
Bosses at the Royal Infirmary, Edinburgh (RIE) would say only they had agreed "a refinancing package" with Consort Healthcare, the firm that has come under fire for charging patients up to 10 a day to park at the hospital since it opened in 2002.
One part of the deal NHS Lothian did make public was that Consort was to cut daily parking charges from 10 to 7.
Politicians and trade unions accused the health board of trying to hide the details of its new deal with Consort - which could be longer and inevitably more expensive than the original PFI deal - by making a fanfare announcement about the reduction in parking charges.
Together with the city's Western General Hospital, the RIE still operates the most expensive parking charges for patients and relatives in Scotland.
A spokesman for NHS Lothian said details of the agreement were "commercially confidential", but insisted it would "deliver multi-million pound gains" for NHS Lothian.
Shona Robison, the SNP health spokeswoman, said: "Secrecy and waste have been the hallmarks of PFI contracts.
"Taxpayers are entitled to see what the terms of the new deal are, given that they are the ones paying for the new contract.
"We are all entitled to know whether Consort have made significant financial gains out of re-negotiating this contract with NHS Lothian and they should publish the terms of the deal for all to see."
Ms Robison said she welcomed the cut in parking charges, but added: "They were a classic example of the bad deal which PFI represents for staff, patients and the taxpayer.
"The fact that there has had to be a renegotiation of the contract at this stage due to public outcry reinforces that."
The public service union Unison suggested the deal would mean a longer association with Consort which would, in the long run, cost taxpayers more.
Tom Waterson, of Unison's health services group executive, said: "While the reduction in parking charges is welcome, I would certainly not class it as a victory for patients.
"The NHS is still giving millions of pounds to a private company which continually refuses to disclose how much profit it is making from the health service and patients.
"If this deal is really making multi-million pound savings for taxpayers, it is time they opened up the books and showed us. What do they have to hide?
"Until then we must assume the deal has been extended, so while repayments are less on a yearly basis, over the piece they will cost taxpayers more."
Bob Anderson, NHS Lothian interim chairman, said: "Throughout our negotiations we have been absolutely determined to get agreement on a reduction in maximum car parking charges as we know they have caused real difficulties.
"Refinancing of the PFI project will now be taken forward and while final details have still to be arranged, I can say it is expected to deliver multi-million pound gains for NHS Lothian.
"Negotiations over the cost of services such as catering and maintenance have also resulted in a very good deal."
Reaction to the new deal from patients' groups was cool. A spokeswoman for Macmillan Cancer Support said: "Whilst a reduction in the cost of parking to 7 is a welcome starting point, there is still a long way to go if we are to ensure that people affected by cancer are exempt from all parking charges."
Margaret Watt, of the Patients' Association Scotland, said: "This hospital may think they should be applauded, but as far as the association is concerned they do not deserve a single clap. This is a commercial stunt to cover up an ongoing tax on the sick."
The cost of parking at hospitals is creeping upwards.
At Ninewells Hospital, Dundee, above, the daily charge is due to rise by 10p to 1.60.
At Raigmore Hospital, Inverness, below, it costs 1 per day or 7 per week.
NHS Grampian has provoked anger by imposing a 5 fee for anyone parking at Aberdeen hospitals for longer than five hours. However, the charge is waived if motorists can produce an out-patients appointment card.
In Perth, the Royal Infirmary, below charges 1.20 and Glasgow Royal Infirmary 1 an hour.