The migrants are aboard two charity ships, Ocean Viking and Open Arms.
The former is run by Doctors Without Borders with Franco-German charity SOSMediterranee.
They rescued eighty-one people last Sunday and another hundred and five on Monday, totalling 356 people.
Spanish Open Arms has been at sea for the past 12 days and still waiting for a safe port to disembark the 151 rescued migrants.
Eight people with health issues were taken by a rescue dinghy to Malta on Monday.
Italy has said “Spain should accept the Open Arms and has maintained its closed ports policy”.
Spain’s Socialist government accepted the Aquarius rescue boat last year after a similar stand-off.
However, it has since hardened its position, saying the Open Arms should look for a closer port.
Last week, European Union’s executive called on member states to show solidarity and find a solution for the ships.