“These attacks are unprecedented since the end of World War II. Having disagreements is one thing; using the relationship for election purposes is another,” a terse statement from the French government said.
The move appears to have been sparked by the decision by Italian Deputy Prime Minister Luigi Di Mao to meet with supporters of France’s “yellow vest” movement -- which has held weekly protests against French President Emmanuel Macron’s policies.
Di Maio said that his populist 5-Star Movement, which is part of a government coalition with the nationalist League, said that it was ready to help the protesters.
"The most recent intrusions constitute a further, unacceptable provocation. They show a lack of respect for democratic choice by a nation that is our friend and ally. They show a lack of respect between democratically and freely elected governments," the French statement said.
It was the latest shot fired at France by Di Maio, who last month said that an NGO rescue boat carrying migrants near Italy should go to Marseilles instead.
"The Mediterranean is not only about Italy, Greece or Spain. But France too. And it has to do its part," he said.
That came after Di Maio sparked a diplomatic incident when he said that France “impoverished” Africa and said that “in order to keep the Africans in Africa, it would be enough for the French to stay home.” France's foreign ministry summoned the Italian ambassador in response to Di Maio’s remarks.
His coalition counterpart and Interior Minister Matteo Salvini backed Di Maio and said France “has little to get angry about because it has turned back thousands of migrants, including women and children, at the border."
"I don't take lessons on humanity and generosity from [French President Emmanuel] Macron,” he later added.
The spat comes ahead of the European Parliament elections in May, where nationalists on the continent are hoping to win big and shift the balance of power to a more skeptical view of mass migration in particular.
“The European election campaign is no justification for a lack of respect toward any nation or its democracy,” the French statement said.
Salvini has said that he hopes French voters send a message to Macron in the elections by showing their support for Macron’s 2017 right-wing presidential rival Marine Le Pen.