Over 1,500 migrants have been rescued off Libya in 11 separate operations, the Italian coastguard said Friday, bringing the number of people plucked from boats in 36 hours to more than 3,500.

The migrants were plucked from 10 dinghies and a fishing boat by the coastguard and navy after a break in bad weather sparked fresh attempts at the perilous Mediterranean crossing.

The rescue followed a lull in arrivals caused by stormy seas, during which only around 400 migrants were picked up in over 10 days -- a startlingly low number compared to the summer months, when an average of 760 people a day were rescued.

On Thursday, nearly 2,000 migrants were rescued in 11 operations which saw a Doctors Without Borders (MSF) boat come to their aid, along with two vessels taking part in the EU's Operation Sophia, which patrols the sea for people smugglers.

The International Organization for Migration estimated in late November that nearly 860,000 migrants had landed in Europe so far this year, with more than 3,500 dying while crossing the Mediterranean in search of safety.

According to the United Nations, the number of migrants crossing the Mediterranean to Europe fell by more than a third last month, due to bad weather and a Turkish crackdown on traffickers in the Aegean on the route into Greece.

MSF said Thursday it had launched a joint operation with environmental group Greenpeace to rescue people risking their lives on the crossing between Turkey and Greece.