The Italian coastguard is using planes and helicopters to spot migrants’ bodies around the boat which sank off the island of Lampedusa on Thursday.
Bad weather is hampering divers. So far, 111 bodies have been found, 155 people have been pulled out alive, but more than 200 are said to be in the seas close to the Mediterranean island.
The boat was carrying some 500 people – mostly from Eritrea and Somalia.
Italy says it will amend immigration laws and has called for European help.
The 20m (66ft) vessel began taking on water when its motor stopped working as it neared Lampedusa on Thursday morning, survivors said.
Some of those on board then reportedly set fire to a piece of material to try to attract the attention of passing ships, only to have the fire spread to the rest of the boat.
The boat – which set sail from the Libyan port of Misrata – is thought to have capsized when everyone moved to one side.
Video footage later showed the vessel sitting upright on the seabed some 45m (150ft) below the surface.
The skipper of the boat, a 35-year-old Tunisian, was arrested. It has emerged that he was deported from Italy in April.
Of the bodies recovered so far 58 were men, 49 were women and two were children of one and six years old. Italian officials say there could be more women in the sunken boat than men – among the 155 survivors only four were women.
Divers are hoping to resume the search in the coming hours, officials say.
“Though the bad sea conditions persist, our guys are ready to go down if a window opens up that makes it safe for them,” coastguard spokesman Filippo Marini said.
The operation had initially focused on an area off Lampedusa called Rabbit Island, but the search was then widened beyond the initial radius of four nautical miles in an effort to recover bodies that had been swept away by tides.
The divers have been describing seeing horrific scenes inside the wreckage.