Updated

Four survivors have told how some 126 fellow migrants drowned off Libya last week when their flimsy rubber dinghy foundered after smugglers removed the engine and fled, the U.N. migration agency said Monday.

Flavio Di Giacomo of the International Organization for Migration said the survivors were interviewed in Sicily after an Italian coast guard ship brought them to Palermo's port Monday.

The two Sudanese and two Nigerian survivors told authorities that a few hours after the migrant smugglers' dinghy set off from Libyan shores Thursday night, the crew removed the engine and left in another boat. The migrant boat quickly foundered. The survivors said some 130 people, most of them Sudanese, had been aboard.

A Libyan fishing vessel, passing by chance, rescued the four and put them on another dinghy, also crowded with smuggled migrants, that was nearby. That boat itself was found by rescuers, and all the passengers were eventually transferred to the coast guard vessel.

The survivors were "very shocked, very confused," when authorities spoke with them, said Di Giacomo. To seek confirmation of their account, authorities interviewed the survivors of the other boat, who confirmed that the fishermen had put the four onto their own vessel.

"Every so often it happens, survivors from one migrant boat are put onto another," Di Giacomo told the AP by phone. He said authorities didn't realize when the migrants were brought ashore that the four had been mixed in with the survivors from another boat.

The coast guard ship brought a total of nearly 1,100 rescued migrants — saved in various separate operations in the central Mediterranean in the past few days — to Sicily, where they will have medical checks and be interviewed as part of the process to eventually seek asylum.

Over the past few years, hundreds of thousands of migrants, fleeing conflict, poverty or persecution, have been rescued at sea from unseaworthy smugglers' vessels that set off from Libya, and brought to Italian shores.