The fast-food chain McDonald's, which farmers see as a 'symbol of bad American eating habits', is taking the brunt of the attacks.

Farmers union leader Jose Bove is currently being held in custody in Montpellier after an attack on a restaurant construction site.

Four other farmers have been released on bail of 105,000 francs each after the incident in the town of Millau in the Aveyron region a week ago.

French farmers are known for high profile protests in the past

The US imposed the new duties - reported to be costing France around $28m - in retaliation against Europe's refusal to accept US beef from cows treated with growth hormones.

'Hit by trade war'

On Tuesday, farmers reportedly blocked access to a McDonald's restaurant in Cahors and handed out local produce to would-be customers. There have also been protests in Seine-Maritime, it is reported.

"We are directly hit by the trade war over the hormone-treated beef, we are victims of American blackmail," Alain Soulie, president of the milk and sheep producers' association, was quoted as saying.

'Victim of visibility'

And another famous US product has also been targeted. Cafe owners in the town of Rodez have reportedly boycotted Coca-Cola, while the mayor in Saint-Pierre-de-Trivisy, a small town in the Tarn district, is said to have imposed an anti-Coca-Cola "tax" on sales of the drink at a municipal aquatic park.

The protest went on after Bove handed himself over to police

Director General of McDonald's France, Philippe Labbe said the fast-food chain was a "victim of its visibility".

He said 90% of the ground beef used in the burgers was produced in France.

France hardest hit

He said: "Hormones in beef, the trade in Roquefort, foie gras and truffles doesn't concern us. Our only concern is to feed more than a million French people each day.''

Aveyron produces the Roquefort cheese and some of the foie gras and truffles that are on the US hit list. German and Danish pork, Italian tomatoes and Italian truffles are also affected.