In a further broadside against McDonald's, the Prince is reported to have made negative comments about the restaurant chain to nutritionist Nadine Tayara and journalists during a visit to a medical school in Abu Dhabi yesterday.
He said: "Have you got anywhere with McDonald's? Have you tried getting it banned? That's the key."
The Prince, who is a strong supporter of organic farming and fresh produce, has restated his views on healthy eating but his remarks have been met with dismay by McDonald's, which branded the criticism "disappointing".
Nick Hindle, spokesperson for McDonald's, said that younger members of the Royal Family "have probably got a more up-to-date picture of us", referring to the Prince's son Harry being spotted eating at McDonald's in 2005.
Hindle said: "This appears to be an off-the-cuff remark in our opinion. It does not reflect our menu or where we are as a business."
A spokesperson for the Prince of Wales said: "[The Prince] was keen to emphasise the need for children to enjoy the widest variety of food and not to eat any particular sort of food to excess."
However, the criticism will come as a further blow to McDonald's efforts to reposition itself as a more health-conscious and ethical retailer ahead of Ofcom's restrictions on junk food ads, which will be introduced on April 1.
McDonald's signed a £1m in January to buy coffee from South and Central America farm co-operatives, in an attempt to improve its image as an ethical retailer.