The regional president of the northern Italian region of Lombardy has refused to accept any more migrants in to the province in comments backed by other regional leaders.

Roberto Maroni of the right-wing Lega Nord, or Northern League, said he had instructed mayors and other officials in his region on Monday to refuse to accept any more migrants allocated to them by the central government.

Municipalities that refuse to comply with the order will have their funding cut, Maroni, who presides over Italy's most populated region, said.

Maroni asked followers on Twitter if they agreed with him that "Lombardy mayors must refuse to welcome clandestine migrants" or face the punitive measures.

Giovanni Toti, the newly elected president of Liguria, also in the north, backed that stance. "We will not receive any more migrants," he said.

Maroni was also backed by Luca Zaia, the right-wing president of Veneto, who said the region, which includes Venice was "like a bomb ready to go off".

"The social tensions are absolutely crazy," Zaia said, according to the AFP news agency.

The pressure on the government is not limited to the north, mayors of Sicilian and other southern towns have warned for months they've run out of room for migrants.

Thousands of those rescued are being resettled in shelters in central and northern Italy while their asylum requests are processed, amid sharpening criticism from anti-immigration parties there.

The comments came as European navies saved nearly 6,000 migrants attempting to make the journey through to Europe, the Associated Press news agency reported.

The number included 2,371 who were saved on Sunday from 15 boats that ran into difficulty shortly after smugglers set off with them from Libyan shores, the Italian coastguard said.

Tens of thousands of would-be migrants fleeing war, oppression, and poverty, have attempted to make the journey across the Mediterranean, and thousands have perished trying to do so.