The warning came as Italy’s EU representative, Maurizio Massari, warned in a letter to the bloc the situation had become “unsustainable”. Prime Minister Paolo Gentiloni has accused other European nations of “looking the other way”, an estimated 10,000 people are believed to have attempted the journey from North Africa in the past four days.

Maurizio Massari added “We could deny the landing of boats that are not flying Italian flags and are not part of EU missions,”, so far this year, more than 73,000 migrants have arrived in Italy by sea. But the tally does not account for the roughly 10,000 migrants saved in the Mediterranean Sea in recent days and are still in transit towards Italian shores.

If Italy follows through on its threat, it could affect the work of several non-governmental organisations and non-Italian merchant vessels performing rescue operations in the Mediterranean Sea. A move to deny entry to Italian ports to boats with rescued migrants could also be hard to defend in terms of Italy’s obligations under international law. But it may be a political imperative for the ruling centre-left Democratic party, led by former prime minister Matteo Renzi, which has come under growing political pressure on migration.