Italy allowed 16 of the 150 migrants stranded on board a coastguard ship at a Sicily port to disembark on Saturday, as government officials face questioning over the refusal to let all passengers off, media reported.
The Diciotti vessel has been docked at the port of Catania since Monday night, after the Italian government blocked migrants from leaving in the absence of commitments from the EU to relocate some of them.
Italy on Friday said it would pull its funding for the EU as a "compensatory measure" if the bloc refused to come forward and help with relocating the migrants, sparking a fresh immigration row between the bloc and Italy's populist government.
According to local media, eleven women and five men -- two of whom are said to have tuberculosis -- were given permission by the government to get off, following a request by the port's health authority for doctors to visit those on board.
Prosecutors from Sicily on Saturday quizzed several senior interior ministry officials in Rome to establish who gave the order blocking migrants from leaving the ship, media said.
The United Nations refugee agency (UNHCR) said EU member states should "urgently" provide places for those stranded on the ship.
"In the meantime, UNHCR urges Italian authorities to allow the immediate disembarkation of those on board," it said on Saturday.
A high-level meeting of a dozen EU member states in Brussels on Friday 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 was prepared to cut its EU contributions.
"They want the 20bn euros ($23bn) 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.
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 remarks on Friday.
"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.
EU figures for 2016 say Italy contributed just under 14bn euros to the EU budget -- less than one percent of its gross national income -- while the bloc spent 11.6bn euros in Italy.
"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," Di Maio, who heads the anti-establishment Five Star, said in an interview with state broadcaster RAI.
'We've had enough'
Italy's Interior Minister Matteo Salvini stopped the majority of the migrants disembarking from the ship after they were rescued on August 15, but he allowed 27 unaccompanied minors off the boat on Wednesday.
Opinion polls suggest that Salvini's stance has boosted his far-right League party's approval rating to around 30% -- a more than 10 point jump from its showing in March's election.
It is now level with the Five Star Movement with which it has governed Italy since early June.
However, according to Salvini's own ministry, migrant arrivals are more than 80% down on the same period last year, with just over 19,500 arriving up to August 23, compared to 98,000 in 2017.
In France the presidency called for a "co-ordinated, long-term European mechanism" to distribute migrants that would include Italy. "There are forces in Italy that are looking to co-operate, we want to believe Italy wishes to play the game," the Elysee palace said.