What you need to know:
- But at least seven people drowned as aid workers struggled to rescue more than 1,500 migrants in one operation.
- Medicins Sans Frontiers said its boats Prudence and Aquarius had rescued about 1,000 people on Friday.
Thousands of migrants have been saved from the sea near Libya during one of the busiest weekends of the year for rescue workers.
More than 2,000 people were rescued on Friday and 3,000 on Saturday, the Italian Coast Guard said.
But at least seven people drowned as aid workers struggled to rescue more than 1,500 migrants in one operation.
An eight-year-old boy was among the dead.
An earlier agency report said 20 bodies had been found by the Migrant Offshore Aid Station (Moas), but this was later corrected.
Moas said its rescue started in the early hours of Saturday and continued non-stop into Sunday afternoon.
The group said it rescued at least 453 people, but more than 1,000 remained in danger.
Chris Catrambone — one of the founders of Moas — said the agency requested urgent assistance from the Italian coastguard and other organisations on Saturday morning.
“Members of our team say they’ve never seen anything like this,” the organisation tweeted.
Italian NGO Sea Eye and the German group Jugend Rettet were also aiding in the rescue efforts.
Medicins Sans Frontiers said its boats Prudence and Aquarius had rescued about 1,000 people on Friday, during which one migrant reportedly died.
The improving Spring weather may have contributed to the sudden surge of sea crossings, analysts say.
The Libyan coastline remains a hotspot for such rescues, as smugglers crowd wooden boats or inflatable dinghies with hundreds of desperate migrants, mainly from the Middle East and Sub-Sahara.
At least 97 migrants died on Thursday when their boat sank.
Just 23 men were rescued, clinging to a flotation device. In late February, the bodies of 87 people washed ashore in a Libyan city.
Though the Mediterranean migrant crisis has subsided from its 2015 peak, the Libyan trafficking has prompted EU leaders to agree a plan of action.
They gave €200 million to the UN-backed government to reinforce its coastguard and disrupt people-smuggling networks.
But the Libyan Government has limited control over the largely lawless strife-torn North African nation, and human rights groups argue that turning refugees away and forcing them back to the dangers of Libya is unacceptable.
The UN estimates that 32,750 people have arrived in Europe by sea so far this year, despite the dangerous winter weather.
An estimated 826 are dead, or missing.