It is not the first time that the leader of Italy's far-right League party has accused Malta of shirking its responsibilities when it comes to handling the constant flow of migrants from North Africa.
According to Salvini's ministry, late on Wednesday Italian authorities alerted Maltese partners to a boat with 13 migrants in Maltese search and rescue waters, which had run out of fuel.
The same migrant boat arrived in Sicily's Lampedusa on Friday, and told Italian police that they were helped at sea by people with uniforms "like those of the [Maltese] coastguard."
The migrants were supposedly approached by a dinghy, given water, two tanks of fuel, life jackets and a compass, and escorted for about an hour towards Italy.
In a statement, Salvini called it a "hostile act" and compared it with recent reports of France pushing back migrants at the Italy-France border.
"Some EU member states don't care about migrants and dump them on us, while Brussels is threatening sanctions over our budget: We will not be intimidated," he said.
In a change to previous policy, Italy's government - in power since June - has been blocking migrant rescue boats from docking in its harbours.
Malta's Interior Minister Michael Farrugia urged Salvini to stop criticizing Malta for doing its duties and start taking note of what Italy should do better for the safety of migrants at sea.
"It is #Italy that repeatedly fails to comply with applicable [search and rescue] conventions and international obligations. #Malta has always followed all obligations and respected the principle of the
nearest place of safety," Farrugia tweeted.
He said Salvini should understand that migrant boats on the high seas are not always in distress. "If persons on board refuse to be rescued, no [search and rescue] authority can prohibit them from continuing their journey," he wrote.
A man holds an effigy of Italian Interior minister and deputy PM, Matteo Salvini, reading in Italian the conjugation of the verb ,To Migrate, during a march of people, including employees of the country's social and reception centers and members of anti-racism associations, against the government's social politics, its recent decree restricting the right to asylum, and against racism.
Italian Interior Minister Matteo Salvini has accused Maltese authorities of helping boat migrants to reach Italy rather than taking them in themselves.
