The woman who died was a farmer in her 30s. Her husband and teenage daughter, who were with her at the protest, were severely injured.

The three people in the car have been arrested as police investigate whether the crash, in the Ariege region, was deliberate or accidental.

The woman was part of a roadblock holding up traffic on the N20 in Pamiers.

She was sitting on a haystack, which had been used to obstruct the road, at 5.45am when it was hit by the car.

The prosecutor has opened an investigation, with the 44-year-old driver being held on suspicion of involuntary homicide. He passed tests for both drugs and alcohol.

Protests are growing across France as farmers put pressure on the government to deal with long-standing grievances.

These include low wages, burdensome regulations, fuel taxes and the impact of EU-enforced environmental rules that, they say, place even greater pressure on the sustainability of their businesses.

The protests echo similar movements in other European countries. German farmers have blockaded roads in recent days while there have also been similar protests in the Netherlands, Poland and Romania.

Farmers' union leaders have now met with the French prime minister, Gabriel Attal, who was only appointed to his job a fortnight ago.

"We told him we wouldn't settle for words," said Arnaud Rousseau, head of FNSEA, France's largest farming union.

"We won't lift the roadblocks as long as the prime minister does not make very concrete announcements," said Arnaud Gaillot, head of the Jeunes Agriculteurs, the union representing young farmers.

"The time for talking is over - action is needed."

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The farmers have received wholehearted support from Marine Le Pen's far-right Rassemblement National party, whose president, Jordan Bardella, accused French President Emmanuel Macron of plotting "the death of French agriculture".

"I am glad that Mr Bardella developed an interest in agriculture over the weekend," said Marc Fesneau, the government's agriculture minister.

EU agriculture ministers are meeting today in Brussels, as the movement threatened to grow across Europe in the coming weeks.