A relative of French first lady Brigitte Macron has been beaten up outside her family's chocolate shop in an apparent politically motivated assault that sparked widespread condemnation on Tuesday.

Jean-Baptiste Trogneux was attacked on Monday evening while returning to his apartment above the famed Trogneux chocolate shop in Amiens, northern France.

The 30-year-old was surrounded by anti-government protesters who insulted "the president, his wife and our family" before attacking him physically, the victim's father, Jean-Alexandre Trogneux, told AFP on Tuesday.

"They've crossed the line. I'm flabbergasted," Trogneux said, later telling the BFM channel that his son had been left with several broken ribs, a head injury and a hand wound.

Brigitte Macron issued a rare statement condemning the "cowardice, stupidity and violence" of the assault, while President Emmanuel Macron called it "unacceptable" as he arrived for a European meeting in Iceland.

"I am in complete solidarity with my family and have been in touch constantly since 11 pm yesterday," Brigitte Macron added.

Local police said they had arrested eight people over the assault, which took place after protests in the city centre during a televised interview by President Emmanuel Macron on Monday evening.

Brigitte Macron's family have run the Jean Trogneux chocolate shop in the centre of her home city of Amiens for six generations, specialising in a local almond-based treat known as the Amiens Macaron.

(AFP)

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