The decision by Italian interior minister Matteo Salvini, who is also head of the far-right League party, represents an opening gambit to make good on his electoral promises to halt the flow of migrants into the country.
Italy has long demanded that the European Union change its migration policy and make good on promises to accept more refugees, saying that Italy has been left alone to coordinate rescues and accept tens of thousands of migrants a year for asylum processing.
"To politely raise one's voice pays off", Salvini told a news conference in Milan. If they're going to refuse to accept refugees picked up at sea, what basis do they have to criticize Italy for balking at taking in hundreds more of them every day?
The migrants were left stranded at sea, with no idea where they might land until Spain's new socialist prime minister, Pedro Sánchez, intervened on Monday to offer the migrants safe haven in Valencia.
They were taken on board its ship Aquarius, which is now between Malta and Sicily. More than 1.8 million have entered Europe since 2014.
Among the passengers on board the Aquarius ship - belonging to the humanitarian group SOS Mediterranee - are 123 unaccompanied minors and seven pregnant women.
"Maltese Prime Minister Joseph Muscat thanked Sanchez and said Italy had "(broken) global rules and caused a standoff". "This is a European issue", he said on Twitter. "Encouraging change in humanitarian policy from (Sanchez's) government", Barcelona Mayor Ada Colau wrote on Twitter after the government's offer. But at the same time, the responses of other nations in the region seem to support what Italy's Interior Minister is saying.
The UNHCR says migrants aboard the rescue ship Aquarius are in distress, running out of provision and urgently in need of help. Picture taken June 9, 2018.
A French NGO's rescue ship, the Aquarius, was waiting for a port to dock at on Monday as a diplomatic standoff played out over where it should go next.
Writing on his Facebook page, Salvini said: "Malta takes in nobody".
"The island can not continue looking the other way when it comes to respecting global conventions", said the statement, which was signed by Salvini and transport minister Danilo Toninelli, who is nominally in charge of the ports.
Mayors across southern Italy say they're prepared to admit the migrants. "We are nonetheless prepared to take care of the rescued people until we are".
The 77-metre ship, the Aquarius, was effectively stranded on Monday in worldwide waters in the Mediterranean, between Sicily and Malta, while its captain tried to find a secure port. Salvini had earlier issued a joint statement with Italian Transportation Minister Danilo Toninelli of the 5-Star Movement, saying Malta "cannot continue to look the other way when it comes to respecting precise worldwide conventions on the protection of human life". He announced plans to cut the budget for reception centers for asylum seekers and, in an unnerving call-and-response with the excited crowd, said that sending all irregular migrants back home was a top priority.