The violent demonstration, which led to farmers' leader Jose Bove being jailed, was in protest at an American boycott on some French agricultural products.

President Chirac - in a speech to farmers in eastern France - said that the farmers' anger arose from a just concern, though he described the form of the protest as unacceptable.

"It would be in nobody's interests to allow one single power, albeit a respectable and friendly one, to rule undivided over the planet's food markets."

It was understandable that French farmers were angered, he said, "when sales did not even cover production costs."

'Just price for labour'

French farmers are noted for taking direct action

"Such situations cause anger, which sometimes may be unacceptable in their form but which take root from a farmer's hopes of a just price for his labour."

Anti-American feeling has been growing in France after Washington imposed a ban on French produce like foie gras, Roquefort cheese and Dijon mustard.

Tit-for-tat sanctions

The protests culminated in a number of farmers smashing up a McDonald's restaurant being built in the town of Millau.

BBC Paris correspondent John Sopel says Jose Bove, who was jailed over the attack, is now being feted as a hero by many agricultural workers and politicians too, ever-conscious of the importance of the farming lobby.