An aristocrat is suing the French state for €351 million (£314 million) in damages for allegedly depriving his family of the throne of Monaco in order to stop it falling into the hands of a German.

Louis de Causans says that in the early 20th century France threatened to annex the wealthy Mediterranean principality if it did not change its rules of succession.

Monaco complied, thus depriving Mr de Causans’ branch of the family of his birthright and giving another offshoot of the Grimaldi family control over the city-state on the Riviera.

"Normally, in my milieu, we remain discreet and we don’t like to stir up this sort of thing. But the truth must be established. Is is a question of honour,” said Mr de Causans, whose full name is Louis Jean Raymond Marie de Vincens de Causans.

But he insisted that he was not aiming to dethrone his cousin Prince Albert, the current monarch of the principality and head of the princely house of Grimaldi, despite the fact that he believes that his own uncle should be on the throne today.

“I have nothing against Prince Albert, who had nothing to do with all of this. It is France which caused the damage,” the 44-year-old told Le Parisien newspaper.