More than 1,400 migrants were plucked from the Mediterranean in the last 24 hours, Italy's coast guard said on Thursday.
These latest rescues come as EU leaders gather in Malta for a summit on stemming the flow of boats from North Africa to Europe.
The coast guard said more than 1,300 people had been rescued on Wednesday in 13 makeshift boats.
At dawn on Thursday, a humanitarian ship chartered by SOS Mediterranee and Doctors Without Borders (MSF) rescued 100 others.
Picked up 22 nautical miles (41 km) off Sabrata, the rescued migrants – travelling with only an old compass to help them navigate and no life jackets – said there were other boats needing help.
MSF said rescue teams are searching for them.
The EU aims to shut down the flow of migrants out of Africa in what is part of the world's worst migrant and refugee crisis since World War II.
Closing the smuggling route from Libya to Europe is "within our reach," EU chief Donald Tusk said Thursday.