A group of 27 people rescued yesterday "said that there were another 75 people on board the boat they were travelling on, who are therefore believed lost at sea," the agency said in a statement.
Accounts of the shipwreck were gathered by UN workers in Sicily who spoke to survivors recovered by Italy's "Mare Nostrum" ("Our Sea") rescue operation.
"According to the information gathered so far, the shipwreck occurred because the rubber dinghy they were travelling on was in a poor state and was overcrowded," Catania prosecutor Giovanni Salvi was quoted as saying by Italian media.
The number of migrant arrivals has now soared past the record 63,000 set in 2011 during the Arab Spring uprisings, and EU border agency Frontex has warned that calm seas across the summer will encourage many more to attempt the trip.
