The sea crossing between Libya and Italy has been attempted by an increasing number of migrants trying to reach Europe this year.
A Spanish navy ship was dispatched to help two migrant boats struggling to stay afloat near Libya on Saturday afternoon, and at sundown it found three other rubber dinghies transporting migrants in the area, Spain's Defence Ministry said in a statement on Sunday.
Passing Libyan fishermen rescued the Sudanese pair along with two Nigerian men who were the only other survivors, and put them on another migrant boat.
"They stole the motor - something which has happened a few times recently - and at that point, the boat started to take on water and sank".
More than 2,200 migrants were rescued from rickety boats by the Italian Navy, private charity boats and worldwide military ships in the Mediterranean this weekend, IOM said.More news: Acceptance and diversity get major stage time at MMVAs
Over 120 migrants are missing following a shipwreck in the Mediterranean Sea, the International Organization for Migration (IOM) said, Sputnik reported.
This comes after the Italian Coast Guard said Sunday that it rescued 730 migrants in the central Mediterranean in seven different operations, with the help of Save the Children NGO and Jugend Rettet.
Among the migrants rescued in the Strait of Sicily were 751 men, 160 women - including one with severe burns - and 185 minors, coastguard and port officials said.
Gangs in Libya have built a lucrative trade out of packing migrants into rickety boats heading for Italy, where more than 65,000 have arrived so far this year.