Decisions about how to spend bequests were made in private

The call comes after it was revealed up to �400,000 of bequests and donations had been spent on replacement uniforms for staff in 2004.

The health authority's endowment trustees, who are responsible for administering the funds, have always met in private.

Union officials have called for more information to be made public.

Detailed information

Holding meetings in public was recently ruled out by the board of trustees, which instead voted in favour of holding one meeting per year in public.

It would be used to publish all the spending decisions made in the past 12 months.

Robin Hunter, from the Dundee branch of the Unison union, said he thought the decision to continue meeting in private "was an error in judgement".

If the trustees think what they have done is right, they should have no problem making this available to the public Robin Hunter Unison

He told the BBC Scotland news website: "The most obvious way to resolve this issue in a constructive way is for the trustees to make public detailed information on exactly what the endowment fund is spent on.

"Any move towards transparency is a good thing, but I think once a year is not enough.

"It seems to me that the business of the endowment fund should be as open as the full NHS budget, which means that the full information should be made available around every meeting of the trustees.

He added: "If the trustees think what they have done is right, they should have no problem making this available to the public."

NHS Tayside's head of communication Shona Singers said there were already plans in place to make that happen.