Senior figures at NHS Tayside were "misled" about the true state of the organisation's finances, NHS Scotland chief executive Paul Gray has claimed.
He told a committee hearing at the Scottish parliament he was "very unhappy" about what had happened.
Mr Gray told MSPs he expected NHS Tayside would require a further Scottish government loan of £9m-£12m.
A review of the board's finances found it had "misrepresented" its finances from 2012 to 2017.
Giving evidence to the Public Audit Committee at Holyrood, Mr Gray said: "I do not wish to present to the committee some analysis that says this is a good situation. It is not. It is something about which I think... to call it disappointed would be putting it mildly.
"These transactions were in my view carried out in a way which was intended to obscure them from the board of NHS Tayside and that is what happened.
"Checks and balances will deal with it up to a point but we're reliant on honesty and integrity."
The review by Grant Thornton found that, from 2012 the board had been "holding" funds allocated to eHealth initiatives.
In the year 2016/17, the money was used to offset general expenditure, making its financial position look more favourable.
SNP MSP Colin Beattie put it to Mr Gray that the board had effectively been misled.
"I would say so," he replied.
NHS has already requested a £4m loan from the Scottish government in 2017/18.
This was in addition to a brokerage of £33.2m the previous year.
Mr Gray added: "As we close off the end of this financial year which we are now approaching my expectation is that I will provide brokerage to Tayside in the range of £9m to £12m. That will take the overall brokerage into the 40-millions.
"Will we get it back? Do I have confidence? I have a strong expectation that we will get it back, my confidence will increase over time.
"Has it been detrimental to the rest of the NHS? No."
The MSPs were told the board's director of finance Lindsay Bedford had been suspended. An internal investigation was launched before Mr Bedford decided to retire.
NHS Tayside chief executive Lesley McLay said: "There isn't anybody more disappointed to be here in front of the committee on this issue.
"There is a level of accountability, clearly I am the chief accountable officer, but I also delegate and there is a level that you have to trust."
The committee also heard from board chairman Prof John Connell who expressed his "extreme disappointment" at what had happened.