Italy postponed high-level talks with France on Wednesday after Paris branded Rome irresponsible for refusing to take in a migrant rescue ship.
Italy's new economy minister shelved a meeting with his French counterpart in Paris as their countries traded barbs over the treatment of more than 600 migrants rescued off the Libyan coast at the weekend.
The migrants were stranded on the NGO vessel Aquarius until Spain said the ship could land at its port of Valencia. It is expected to arrive there late on Saturday.
French President Emmanuel Macron accused Italy's new populist government of "cynicism and irresponsibility" for closing its ports to the 629 migrants.
Rome called his comments "unacceptable" and summoned France's ambassador on Wednesday.
"Such statements are undermining relations between Italy and France," Italy's foreign ministry said in a statement.
Macron later appealed for the two sides not to "give in to emotions that certain people are manipulating".
In a speech in the western French town of Mouchamps, he insisted that France was "working hand in hand with Italy" to handle migration.
Italy's far-right Interior Minister Matteo Salvini had suggested that a planned meeting between the leaders of the two countries should be cancelled if France did not issue an "official apology".
"If an official apology doesn't arrive, Prime Minister (Giuseppe) Conte would be right not to go to France," Salvini told reporters.
A French presidential source said the country had not received any formal demand from Italy for an apology.
Conte and Macron are due to hold talks on Friday ahead of a European summit. Late Wednesday Italian media citing sources said Conte was leaning toward postponing the meeting, rather than cancelling it.
Their talks are meant to focus on the contentious issue of migration.
The European Parliament's president on Wednesday said the contentious issue was threatening "the survival" of the 28-nation bloc.
"The EU's own survival depends on the handling of migration," Antonio Tajani tweeted, calling it "the biggest challenge of our times."
Italy's new Economy Minister Giovanni Tria meanwhile announced he was cancelling a meeting with his French counterpart Bruno le Maire in Paris. But the French economy ministry later said the ministers had "agreed that Mr Tria will come to Paris in the coming days".
European Union member states are deeply divided over how to deal with asylum seekers.
Austrian Chancellor Sebastian Kurz on Wednesday hailed cooperation between the hardline interior ministers of Austria, Germany and Italy on the issue.
"I think it marks very sensible cooperation that will contribute to reducing illegal migration to Europe," said Kurz, whose country assumes the EU's rotating presidency on July 1.
"We believe an axis of the willing is needed to fight illegal migration."
EU leaders in December set an end-June deadline for an overhaul of rules to create a permanent mechanism to deal with migrants.
German Chancellor Angela Merkel said Wednesday that the issue of migration was "a sort of decisive test for the future and cohesion of Europe."
The International Organisation for Migration on Tuesday warned against the closing of EU borders.
"I fear a major tragedy if states start refusing to accept rescued migrants," its director general William Lacy Swing said.
Salvini has repeatedly accused fellow EU members of abandoning Italy as it struggles to cope with migrants making the perilous journey from Africa across the Mediterranean.
The country has seen more than 700,000 migrants arrive on its shores since 2013.
In Geneva, the head of the UN refugee agency (UNHCR), Filippo Grandi, also Italian, said Wednesday Italy was "right" to say it could not accept all the migrants crossing the Mediterranean.
Under EU rules, migrants must apply for asylum in the European nation where they first arrive.
Speaking to the Senate Wednesday, Salvini accused France of only receiving 640 of the 9,816 migrants it had promised to take from Italy.
He said that between January and May, France had sent 10,249 migrants back to Italy.
He demanded that France move from "words to action and offer a sign of generosity" by taking more in.
Salvini has accused charities that rescue migrants of working with human traffickers but said Italy would not stop rescuing migrant boats itself.
An Italian coastguard ship carrying more than 900 migrants was allowed to dock in Sicily on Wednesday.
"Closing ports, whoever does it, threatens rescue at sea, as we have seen in the case of the Aquarius, and therefore is not the right solution," UN High Commissioner for Refugees Filippo Grandi told reporters in Geneva.
But he stressed that "the reason why Italy said it had closed ports is something we need to listen to".
Meanwhile, the German NGO Sea Watch said it would take on board the 40 migrants rescued by the US Navy Tuesday off the coast Libya, where 12 other migrants died, but only if Italy agreed to open its ports to NGO vessels.