More than 200 African migrants are believed to have drowned after their boat sank off the Libyan coast last Sunday night.
Libyan navy coastguards reported being able to rescue only 26 of the 250 people who had been on the wooden boat to Italy.
Another 500 refugees from Palestine, Syria, Egypt and Sudan drowned off the coast of Malta last week.
Survivors say traffickers deliberately rammed and sunk their boat.
It is European Union immigration laws that force migrants to resort to ever more risky routes and methods.