BBC correspondent Nicholas Witchell says that perhaps mindful of the stir caused by Prince Charles wearing a silly hat in the Caribbean recently, the officials said there was no way the duke would wear a hairnet.
The duke, who is touring Australia with the Queen, breached hygiene regulations during a visit to a cheese-making factory.
He failed to put on a hairnet as required by the regulations.
While the Queen was carrying out engagements in Sydney, the duke went to the farming town of Wagga Wagga to visit the Charles Stuart University, which boasts its own cheese-manufacturing laboratory.
Silly-hat ban
Officials who went ahead of him were evidently worried about his having to put on a hairnet and bootees, which everyone entering the factory is required to do.
BBC correspondent Nicholas Witchell says that perhaps mindful of the stir caused by Prince Charles wearing a silly hat in the Caribbean recently, the officials said there was no way the duke would wear a hairnet.
Now the cheesemakers, whose ricotta won a gold medal at the Sydney Agricultural Show last year, will have to decide whether the cheese is fit for human consumption.
Cheesemaker Barry Lillywhite said he would be doing tests to see whether it could be saved.
"It would be nice to make a special batch of Prince Philip cheese," he added.
Buckingham Palace said the prince was not required to wear a hairnet and, in any case, the cheese process had been only a test.
The duke was not the only one allowed in without a hairnet: before he arrived, a police sniffer dog went over the entire premises.
A Buckingham Palace spokesman later said any suggestion that the Duke had contaminated cheese was "nonsense".
"The cheese-making was set up as a demonstration and there was no requirement for the Duke or any member of his party - or the media - to wear sterile clothing," said the spokesman.