“This new provocation is unacceptable between neighbouring countries and partners at the heart of the European Union,” a ministry spokesman said in a statement a day after Di Maio met the protesters on French soil.
“Mr Di Maio, who has governmental responsibilities, should ensure that he does not impair with its repeated interferences our bilateral relations, in the interest of both France and Italy,” the spokesman said.
Di Maio, head of the anti-establishment Five Star Movement (M5S), announced Tuesday he had met near Paris with yellow vest leader Christophe Chalencon and Ingrid Levavasseur, who is heading a yellow vest list for European Parliament elections in May.
He invited them and other yellow vests to a follow-up meeting in Rome, claiming on Twitter that “The wind of change has crossed the Alps.”
Oggi con @ale_dibattista abbiamo fatto un salto in Francia e abbiamo incontrato il leader dei gilet gialli Cristophe Chalençon e i candidati alle elezioni europee della lista RIC di Ingrid Levavasseur.
Il vento del cambiamento ha valicato le Alpi. pic.twitter.com/G8E0ypLalX
— Luigi Di Maio (@luigidimaio) February 5, 2019
Tensions have flared between the two countries since the Five Star Movement and rightwing-populist League party came to power in a coalition in Italy last June.
Di Maio had already drawn Paris's ire after he accused France of fuelling the migrant influx to Europe by continuing to “colonise” Africa. That prompted France to summon Italy's ambassador in protest.
And De Maio's fellow deputy prime minister, Matteo Salvini, has lambasted President Emmanuel Macron directly by saying he is “close, with all my heart… to the French people, the millions of men and women who live in France under a terrible government and terrible president”.
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The “yellow vest” protests against fuel taxes began in rural and small-town France in late November, before ballooning into a wider revolt against Macron's policies and governing style.
The French president is hoping to forge an alliance of pro-European centrists ahead of the bloc's parliamentary vote, against a wave of populist movements in several European countries.