Italian authorities were told about the capsized boat by a Libyan oil platform tugboat. According to the coast guard, the boat was carrying about 130 people.
The coast guard ship was already heading to a Sicilian port with 318 migrants on board, saved in a previous mission on Tuesday.
About 941 stricken migrants have been picked up in several rescue operations in the last 24 hours, including 30 children and 50 women, one of whom is pregnant and was taken by speedboat to Lampedusa island. Migrants are heading to Italy from Syria, Tunisia, Libya, the Palestinian territories and sub-Saharan Africa, authorities said.
The search for more survivors is continuing.
