A shipwreck in which about 400 migrants are feared to have died off Libya this week was caused by excitement at the sight of rescuers, survivors say. They told officials that the boat capsized when many migrants moved to one side as a rescue ship approached. Monday's sinking is among the worst migrant tragedies in the Mediterranean.

Aid agencies say not enough is being done to save the lives of the rising number of people trying to cross the sea to Europe.