France has accused Italy of interfering in its affairs after the populist government in Rome, which rode to power last year on a wave of anti-establishment sentiment, offered to help the "yellow vest" movement.

Matteo Salvini and Luigi Di Maio, who are both deputy prime ministers, gave enthusiastic encouragement to the gilets jaunes, whose protests have turned increasingly violent in Paris and other cities.

While condemning violent acts, Mr Salvini, who is also interior minister, said he supported “honest citizens who protest against a president who governs against his people.”

Mr Di Maio, who is the head of the Five Star Movement, offered the protesters the use of his party’s Rousseau system, an internet platform that allows supporters to vote for candidates and propose legislation, eyeing the prospect of the gilets jaunes becoming a nascent political party.

That earned him a sharp rebuke from Nathalie Loiseau, France’s minister for European affairs, who tweeted: “France refrains from giving lessons to Italy. Monsieurs Salvini and Di Maio should first put their own house in order.”