Hundreds of youngsters have enjoyed Auckland museum Motat during the school holidays, but the home of old engines and science gadgets is now the subject of a complaint to the Serious Fraud Office.
And the museum's board is in the dark about who the complainant is or the nature of the complaint.
The Museum of Transport and Technology is the country's largest transport and technology museum, funded by Auckland ratepayers.
It is undergoing its annual audit by the Office of the Auditor General and last week the board became aware of the complaint, but board chair Paul Bayly did not know its source or what it was about.
"I have no reason to understand there would be any substance to it," he said.