Spain's maritime rescue service says it has deployed ships and aircraft in a search for a boat believed to be carrying 27 people in the southern Mediterranean Sea.

The service said a Spanish Navy ship joined in the search Saturday for the boat that is thought to be transporting migrants trying to reach Europe from Africa.

Rescuers on Friday picked up 76 migrants, including 22 who had disembarked from a boat onto a small Mediterranean island and 54 who had been aboard a small boat.

Thousands of migrants try to reach Spain each year either by attempting to enter the country's north African enclaves of Melilla and Ceuta or by making perilous sea crossings to the mainland.