Road blocks were in place for the third consecutive day on Wednesday as French farmers continued to protest against low prices they say have driven them to point of bankruptcy.

With the government due to present details on an emergency plan to help the struggling farmers, the protests, which have seen access to Mont-Saint-Michel blocked by tractors, continue to cause chaos on the roads.

The movement began in Normandy on Sunday and was centred around the town of Caen where farmers blocked the péripherique ring road.

But by Wednesday the movement had spread to other départements with barricades often made of manure and earth being installed on roads in Finistère and Ilé et Vilaine in Brittany as well as in the Pays de la Loire region and even as far south as Auvergne.

In Normandy two key bridges the Pont de Tancarville and the Pont de Normandie were blocked off. In Brittany entrance to the towns of Dinan and Loudéac was cut off.

Access to Mont-Saint-Michel, France’s second most visited tourist attraction remained blocked on Wednesday, although the site was expected to be open. Visitors may have to walk a few kilometres to get there.

On Tuesday tourists were forced to get out of buses and roll their suitcases towards the monastery, which sits on an island and attracts some three million visitors a year.

French news site Le Parisien has a fairly up to date list of all the road blocks in place.

The head of the powerful FNSEA farmers' union, Xavier Beulin, said he expected the protests to continue, adding they “could be extended to other regions on Wednesday.”

(Tourists forced to walk along the road to get to Mont-Saint-Michel. Photo: AFP)

Jean-Pierre Fleury, head of a union representing beef farmers, said: “The farmers will not let up, for the simple reason they are fighting for their lives.”

A combination of changing dietary habits — French consumers are eating less meat — and foreign competition has driven down pork, beef and milk prices.

Farmers blame supermarkets, distributors and the food processing industry for keeping prices low.

On Tuesday farmers were seen taking away non-French meat products from supermarket shelves to demonstrate to the public that they should buy homegrown produce.

Retailers and food industry chiefs had promised to raise prices on meat and dairy after a meeting with farmers last month but the farmers say price hikes in supermarkets have yet to filter down to them.

Stung into action, French President Francois Hollande has promised to unveil an emergency plan later Wednesday.

Agriculture Minister Stephane Le Foll has already hinted measures could include tax breaks and debt relief for heavily-indebted farms.

The government will also publish an eagerly-awaited report by an independent mediator which will decide who is at fault for keeping prices low.

Le Foll has said around 10 percent of farms in France (approximately 22,000 operations) are on the brink of bankruptcy with a combined debt of one billion euros ($1.1 billion), according to the FNSEA.

FNSEA chief Beulin warned that the farmers were expecting “a bit more than trivial measures” from the government on Wednesday.

He called for “a medium- and long-term plan with ambitions and objectives.”