"We must continue to call on European governments to act so that people, such as those rescued by us today, do not die, not in Libya nor in the Mediterranean Sea".
The Malta-based Migrant Offshore Aid Station has rescued between 1,500 and 1,800 in the Central Mediterranean in a major overnight operation.
About 8,300 migrants were rescued in the Mediterranean over Easter weekend, as smugglers took advantage of calm seas and better weather to launch boats to Europe.
Migrants from sub-Saharan Africa fleeing war and poverty have created an opportunity for smugglers, who calculate migrants will be picked up by rescue boats after entering worldwide waters 12 nautical miles off Libya's coast.
But MSF have defended its actions on Twitter, as they claim the same number of migrants would try to cross, even if they weren't there.
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It had said this month that it was reviewing a business it called "non-core" as it looks to pay down debt from Mead Johnson . At the time the group said it was considering "all options" for the unit, which includes French's mustard and sauce products.
The Italian coastguard were joined by five privately-run rescue boats and charities, including the Doctors Without Borders (MSF) vessels Prudence and Aquarius. The rest of the migrants were sent to Calabria on the Italian mainland Sunday.
The Italian coast guard reported launching 19 rescue missions as migrants from Libya attempted to make the trip in rubber dinghies and wooden boats. Zuccaro says he is not acting on behalf of Frontex, but that he is concerned that the rescue vessels are creating an open border into Europe as thousands of irregular migrants reach Italy each year. Of that, more than 650 have died. One man was found dead on one of the rafts.
"This weekend is set to be the latest marker in the record-breaking escalation of this ongoing humanitarian crisis at sea", Moas said. Some 97 migrants are missing in that incident.
As weather conditions deteriorated, NGOs urged more vessels to head to the region, with their own already crammed with around 4,500 people picked up from unseaworthy vessels the previous day in 35 operations.
A Somali migrant carries her 12-day-old baby on board a rigid-hulled inflatable boat.