A Tunisian man is in custody in connection with the shipwreck that claimed the lives of at least 274 Eritrean and Somali migrants, an Italian prosecutor said Tuesday.

Khaled Ben Salam, 35, was among the 155 survivors of last Thursday's disaster off the island of Lampedusa, prosecutor Renato di Natale said during a press conference in Agrigento.

Authorities were led to Ben Salam by testimony from other survivors, who said a "white man" was the boat's skipper, Di Natale said.

Ben Salam is likely to be charged with human trafficking and with multiple counts of voluntary manslaughter, the prosecutor said.

As the skipper, Ben Salam was responsible for allowing too many people aboard the boat and witness accounts indicate that it was he - or someone acting on his instructions - who set a piece of cloth on fire in a bid to attract attention from other vessels once the boat began taking on water near Lampedusa, Di Natale said.

The burning cloth landed on the fuel-covered deck, sparking a massive blaze, and the shift of passengers to one side of the boat to escape the flames caused the vessel to capsize.

Transcripts of witness interviews show the migrants paid between $1,000 and $2,000 each for the voyage to Italy from the Libyan port of Misrata.

"To organize the trip, I contacted a Sudanese man, whom I paid $3,400 in total for my family," said one man who made the trip with three cousins.

While prosecutors prepare charges, Italian authorities continue to search for as many as 100 additional bodies.

Lampedusa, Italy's southernmost point, has become an entry point for undocumented immigrants. EFE