The vessel capsized off the Libyan coast on Sunday, with survivors who were brought to Italy telling charity workers that as many as 400 others perished.
Italian coastguards, who intercepted 42 boats on Sunday and Monday alone carrying 6,500 migrants attempting to make the hazardous crossing to Europe, confirmed that they had saved 145 people from the sunken boat and found nine bodies.
The International Organization for Migration and the charity Save the Children said that 150 survivors of a shipwreck had arrived on Tuesday morning in the southern Italian port of Reggio Calabria, but they were as yet unsure whether they were from the same boat coastguards said had sunk.
Coastguard spokesman Commander Filippo Marini told AFP that they had not found any more "survivors or anything else which would indicate more victims".
He said he could not exclude that more lives had been lost, and said the kind of vessel from which the 145 people were rescued usually carried many more people.
Search operations were continuing Wednesday as part of ongoing naval and coastguard patrols in the area.