Dozens of people have been blocked at the Sicilian port of Catania on the Diciotti vessel since Monday night because the Italian government is refusing to allow them to disembark without commitments from the EU to take some of them in, AFP wrote.
But a high-level meeting of a dozen EU member states in Brussels on Friday, held to discuss what officials said was the broader issue of the disembarkation of migrants rescued at sea, failed to produce an immediate solution for the Diciotti migrants.
"The European Union has decided to turn its back on Italy once again," Deputy Prime Minister Luigi Di Maio wrote on his Facebook page, adding that his country had no choice but to "take a compensatory measure in a unilateral way... we are ready to reduce the funds that we give to the European Union".
"They want the €20 billion ($23 billion) paid by Italian citizens? Then let them demonstrate that they deserve it and that they are taking charge of a problem that we can no longer face alone. The borders of Italy are the borders of Europe," he added.
Di Maio had earlier warned that "if they decide nothing regarding the Diciotti and the redistribution of the migrants, I and the whole Five Star Movement (his party) will no longer be prepared to give €20 billion to the European Union every year."
Migration is a hot-button issue in Italy, where hundreds of thousands of people have arrived since 2013 fleeing war, persecution and poverty in the Middle East, Africa and Asia.
Under EU rules people must seek asylum in their country of arrival, but Italy's new government has increasingly barred boats from docking at its ports.
Brussels quickly hit back at Di Maio's comments.
"Unconstructive comments, let alone threats, are not helpful and they will not get us any closer to a solution," European Commission spokesman Alexander Winterstein told a briefing.
"The EU is a community of rules and it operates on the basis of rules, not threats."
No deal was struck about the Diciotti migrants at the talks, as a source at the European Commission said "this was not a meeting where decisions were taken".
However the source said they discussed "the need for a shared and rapid solution for the migrants on board of the Diciotti as well as those most recently disembarked in Spain and Malta."
EU figures for 2016 say Italy contributed just under €14 billion to the EU budget — less than one percent of its gross national income — while the bloc spent €11.6 billion in Italy.
Di Maio, who heads the anti-establishment Five Star, said Italy did not want the "mickey taken out of us by the union's other countries" on the distribution of migrants.
"The EU was born of principles like solidarity. If it is not capable of redistributing 170 people it has serious problems with its founding principles," he said in an interview with state broadcaster RAI.