The boat carrying the migrants was intercepted by a Spanish oceanographic vessel on Tuesday about 150 nautical miles east of the Sicilian port of Augusta, said the Spanish National Research Council which operates the research vessel said.
The vessel, the Sarmiento de Gamboa, plucked 194 migrants from the ship, including 61 children and 54 women, and gave them water, juice, fruit, yoghurt and blankets.
"They showed signs of dehydration but are otherwise in good health," its captain Maria Angeles Campos told the research council.
The remaining passengers were rescued by an Icelandic coast guard ship taking part in Triton, a European Union coastal patrol operation aimed at helping Italy cope with an influx of migrants crossing the Mediterranean from north Africa.
Signup to our newsletter and follow us on Facebook and Twitter!
Operation Triton is supposed to replace "Mare Nostrum" the Italian navy's search-and-rescue mission.
The Mediterranean has become "the deadliest route of all" for migrants, the United Nations refugee agency UNHCR announced earlier on Wednesday.
UNHCR reported 3,419 deaths in the Mediterranean in attempted crossings this year amid the more than 207,000 people who have attempted the sea crossing since the start of January.
That is nearly three times the previous known high of about 70,000 in 2011, when the Libyan civil war was in full swing, the agency said.
Nearly half of Syria's pre-war population of 23 million people has been forced to flee since the conflict in the country began in March 2011 as an uprising against President Bashar Assad.