A Sicilian boat rescued 13 illegal migrants from a sinking boat south of Malta on Sunday.
It is believed that the immigrants were trying to reach Italy.
The survivors said 17 of their companions were lost at sea, a Maltese army spokesman said.
The nationality of the survivors has still not been determined.
The incident occurred one day after 14 other illegal migrants were rescued by an Italian navy vessel near Sicily. The survivors, who had departed from Libya, said 13 of their fellow passengers died on the way from North Africa.
Italy and Malta are key destinations for Africans who try to flee Africa by sea to seek a better life in Europe.
Libya and Morocco are often points of departure because of their proximity to Europe. But many of these African immigrants have lost their lives in recent months due to the difficult conditions and lack of safety measures.