Survivors say the tragic episode happened after the boat carrying about 550 immigrants overturned a day after leaving Libya.
No fewer than 400 immigrants are feared drowned after their boat capsized off Libya, BBC reports.
Survivors say that the tragic episode happened after the boat, which was carrying about 550 migrants in total, overturned a day after leaving Libya.
Nine bodies have already been recovered, but no more survivors have been found since then.
144 people were reportedly rescued from the capsized boat on Monday by the Italian coast guard, many of whom international children's' rights NGO, Save The Children has said were "young men, probably minors".
Air and sea search operation were also launched in hopes of saving others.
Hundreds more migrants rescued from boats in the Mediterranean are due to arrive in Sicily during the day, even as Italy's interior ministry has instructed officials throughout the country to be prepared to house the new arrivals, many of whom are children.
Over 8,000 migrants have been picked up since Friday, and more boats are heading for the Italian coast.
According to Save The Children spokesman, Michele Prosperi, the migration season has just started and "when the weather improves... we may have many more arrivals".
Officials say 170,000 migrants crossed the Mediterranean to Italy last year and as many as 3,500 died while making the journey.
Meanwhile amid growing concerns that their rescue missions were encouraging migrant crossings, the Italian government scaled back on its maritime rescue operation and a more limited EU border security operation took over.
Also, since the fall of Muammar Gaddafi in 2011, Libya has been without a stable government allowing trafficking networks to thrive.