French President Emmanuel Macron on Tuesday accused Italy of "cynicism and irresponsibility" over its refusal to take in hundreds of migrants stranded on a rescue ship in the Mediterranean, a government spokesman said.
Macron told a cabinet meeting that under maritime law, "in cases of distress, those with the closest coastline have a responsibility to respond," spokesman Benjamin Griveaux said.
Earlier on Tuesday the French government defended its decision not to offer safe harbour to the stranded migrant ship Aquarius after local leaders on Corsica proposed opening one of their ports to the vessel.
Corsican leaders Gilles Simeoni and Jean-Guy Talamoni, the top politicians on the French Mediterranean island, tweeted their offer on Tuesday morning as uncertainty grew over the fate of the 629 people on board the ship.
But the central government in Paris criticised the gesture by the Corsican nationalists.
"[Simeoni] is taking a position without having any responsibility which is easy," junior Europe and foreign affairs minister Jean-Baptiste Lemoyne told Sud Radio.
"What does international law say? They need to go to the port that is safest and closest. And we can see that Corsica is not the closest or the safest. Given the boat's location, it is between Italy and Malta," he added.
Both Italy and fellow EU member Malta have refused to accept the migrants who are now heading for the Spanish port of Valencia after the new Socialist government in Madrid agreed to take them in.
Italy's hardline immigration policy under its new populist government could have knock-on effects in neighbouring France, where President Emmanuel Macron has also tightened immigration laws to crack down on illegal arrivals.
Italian Interior Minister Matteo Salvini -- who is also deputy prime minister -- has promised to deport hundreds of thousands of economic migrants, warning that Italy would not be "Europe's refugee camp".
The country has been the main point of entry in Europe for migrants and refugees arriving from Africa in recent years, with 700,000 crossing the Mediterranean since 2013, often from war-wracked Libya.
Migrants shelter on the Aquarius boat. Photo: AFP
Italy policy 'sickening'
Any increase in arrivals in France would ring alarm bells for Macron who has worked hard to close down migration routes from Africa amid strong anti-immigration sentiment in France.
But a spokesman for Macron's Republic on the Move party said the Italian government's policy was "sickening."
"The position, the line of the Italian government is sickening. It's unacceptable to play politics with human lives which is what is happening at the moment," Gabriel Attal told the Public Senat channel.
"I'm a spokesman for the party, not the government, but I can't imagine that France will not play a role in finding a humanitarian solution for this boat," he said.
Far-right leader Marine Le Pen called for the boats to "return where they came from" and said charities rescuing migrants in the Mediterranean were "the accomplices of the people-trafficking mafia."
Eric Ciotti, a prominent hard-right MP from the opposition Republicans party, also called on the government to take a tough line on the Aquarius.
"No French port, not Corsica, not Nice, not Marseille," he told CNews.
"Of course we should save lives, naturally it's a priority and Europe must act. But the obvious solution is returning to the Tunisian coast or to the Libyan coast," he said.
French charity defiant
The head of the French charity which charters the Aquarius migrant rescue ship said Tuesday that it would continue its operations despite the international standoff over the 629 people currently onboard.
The defiant comments from Sophie Beau, head of the charity SOS Mediterranee, suggest the row over the stranded ship could repeat itself -- not least as migrant attempts to cross the Mediterranean increase in the warm summer months.
Beau told AFP a "one-off solution" had been found for the Aquarius after Spain offered to take in its passengers following refusals from the nearest countries, Italy and Malta.
But the charity's missions will continue "as long as there are people drowning in the Mediterranean, as long as we have the resources, and as long as we are able to act and we are not kicked out of the area," she said.
"The rescues will continue and it is crucial that European countries talk amongst themselves to find acceptable solutions" to bring to shore migrants stranded in the Mediterranean, she said.
Beau said her charity, based in the southern French port city of Marseille, was acting under international law in giving "assistance to people in distress".