Tunisia's official TAP news agency says more than 200 people are missing and two are dead after a fishing boat carrying an estimated 800 immigrants sank off its coast in a storm.
TAP says the fishing boat was believed to have set sail from Libya and was en route to Italy.
The Thursday report said its passengers, which include women and children, are from Africa and Asia.
The boat stalled some 20 miles off the Kerkennah islands in southern Tunisia on Tuesday night in foul weather than also hampered rescue operations.
Some 570 passengers were rescued and authorities attribute the large number of missing from the stampede to get off the ship and board inflatable rafts during the storm.
Survivors were transferred to Choucha refugee camp near the Tunisia-Libya border.