The Advertising Standards Authority (ASA) warned parent company Heineken UK about its emphasis on the beer's connection with France in relation to a television ad featuring footballer Eric Cantona and another press ad.
The press ad said: "If you find a better tasting French beer, we'll eat our berets," and continued: "The French know a thing or two about taste. That's why Kronenbourg 1664 is always brewed with the aromatic Strisselspalt hop for a taste supreme."
The television ad, featuring Cantona, said: "Here in Alsace, things are a little bit different. The hop farmers are treated like the footballers of Britain. They are idolised and adored. And why not? They are living legends. They are the men that grow the noble hops that make Kronenbourg the taste supreme."
Small print in both ads read: "Brewed in the UK".
The ASA received two complaints, one that the ad misleadingly implied that Kronenbourg 1664 was brewed in France and a second that it misleadingly implied that the hops used to produce the beer were grown in France.
Heineken UK said Kronenbourg 1664 was "an inherently French beer" that had first been brewed in 1952 in Alsace by Brasseries Kronenbourg and was now brewed under licence in the UK in a process supervised and approved by Brasseries Kronenbourg.
The company said Kronenbourg 1664 was brewed with the Strisselspalt hop, which to the best of their knowledge was only grown commercially in Alsace, France, and which had been the major aroma hop produced in the area since 1885.
They believed that Kronenbourg 1664 could correctly and reasonably be described as a "French beer" because of its heritage, the origin of its recipe and the use of the Strisselspalt hop, as well as its ownership and the yeast type used.
The ASA said it acknowledged Heineken's arguments as to the beer's heritage and the French origins of the recipe, but "considered that the degree of emphasis in the ad on the connection with France would lead consumers to believe that the entire brewing and manufacturing process took place in that country".
It also found that the Strisselspalt hop was only one of several hops used to create Kronenbourg 1664, saying: "We considered that the degree of emphasis in the ad on the contribution of French hops to the beer, including the statement that the hop farmers in Alsace 'are the men that grow the noble hops that make Kronenbourg the taste supreme' implied that all, or a significant majority of, hops used in the brewing process were sourced from France.
"Although we noted from the documentation supplied that the Strisselspalt hop used by Heineken was sourced from the Alsace region of France, we also noted that it did not constitute a significant majority of the total hops used in the recipe for the beer. We therefore concluded that (the television) ad was misleading."
The ASA ruled that the ads must not appear again in their current form, adding: "We told Heineken UK to take care not to emphasise a connection with France to the extent that their ads implied that Kronenbourg 1664 was brewed in France, or that all or most of the hops used in the recipe were grown in France."