The French President fired a broadside at traditional British cuisine by joking: "The only thing the British have given to European farming is mad cow disease." He added: "You can't trust people who cook as badly as that. Apart from Finland, [Britain] is the country where you eat the worst."
M. Chirac added that France's differences with Nato began after its Scottish former secretary general Lord Robertson offered him a local Scottish speciality, believed to be haggis.
His light-hearted remarks came during talks with the German Chancellor, Gerhard Schröder, and the Russian President, Vladimir Putin, in Kalingrad, Russia, on Sunday, but surfaced in the French newspaper Liberation after being overheard by journalists. The "private" jokes appear to have been intended for a wider audience. French journalists said he knew that microphones were lurking nearby.
The British Government was not amused. "There are some things better not commented on," a Downing Street spokeswoman said.
Mr Blair made a pointed reference to the comments when asked whether the G8 summit at Gleneagles would be an anticlimax after the International Olympic Committee meeting in Singapore, where he is lobbying for London's bid to stage the 2012 Games, and M. Chirac will press the case for the favourite, Paris. "I won't say the G8 Summit would be an anticlimax to it because that would be undiplomatic, and I know when I go there I will be in the presence of very diplomatic people," Mr Blair said.
In Kalingrad, President Putin objected to M. Chirac's suggestion that British cuisine was the lowest of the low. "What about hamburgers?" he asked. "No, no," M. Chirac replied. "Hamburgers are nothing [by comparison]."
M. Chirac's comments echo remarks made by French journalists in recent days as they defended the Common Agriculture Policy (CAP) against Mr Blair's criticism. The newspaper Le Parisien said that a nation which eats "boiled beef with mint" had no right to comment on anything to do with food. However, French farmers have adopted a more positive approach, greeting British tourists arriving at Channel ports with free cheese, fruit and tomatoes.
Even if the French President's remarks were light-hearted, they come at a time when relations between the two leaders are in the deep freeze. They criticised each other after the collapse of the EU's summit in Brussels last month, when Mr Blair refused to surrender Britain's £3bn-a-year rebate on its EU contributions unless France agreed to cuts in the EU's farm subsidies.
The latest diplomatic rift could sour the atmosphere at Gleneagles, where the G8 leaders will gather after the IOC announces its decision tomorrow. Ironically, Britain and France are probably closer than any two other G8 members on the two main issues on the agenda: Africa and climate change. Despite that, British officials are braced for an outburst from M. Chirac, especially if London pulls off a surprise victory over Paris.
Mr Blair also had potential problems over the Gleneagles summit yesterday. Although he is confident of hitting his target of doubling aid to Africa, battles over the wording of the summit communiqué remain. A government source said: "It's not a done deal yet."
One issue is over the timing of the aid boost. Campaigners want an immediate injection of $25bn (£14bn), but the G8 may spread the payment over five years. There are also disputes over the precise figure to be announced.