Italian authorities have dispatched a robot submarine with a video camera to a shipwreck off the Calabrian coast to see if it's carrying radioactive waste dumped by the mob in a lucrative disposal racket.

Calabrian prosecutor Bruno Giordano has cautioned in TV interviews that until the contents of containers on the sunken ship are known, he can't say if the allegations by a mob turncoat about the ship are true.

The robot sub began filming Saturday. On Tuesday, it was still unclear what the cargo held, or even if the ship was the Cunsky cargo vessel that turncoat Francesco Fonti has spoken about to magistrates and in interviews on Italian TV.

No name of the ship is visible, and it wasn't known if someone had removed the name or if algae might have covered up writing.

Giordano said Fonti has claimed the mob sank "hundreds" of barrels of illegally disposed of waste. Fonti was with Italy's Calabrian Mafia, otherwise known as the 'Ndrangheta, or Honoured Society.

The prosecutor, based in Paola, Calabria, has promised that if analyses do turn up toxic substances, the hunt would be on for more sunken ships.

Businesses paid mobsters to dump waste: informant

Fonti claims mobsters made millions of dollars illegally dumping radioactive and other toxic wastes for northern Italian businesses. Fonti has said he himself has been involved in the alleged sinking of three vessels, including the ship the robotic diver is now filming.

In recent interviews, Fonti's face was blackened out to protect his identity, since he is under state protection.

Fonti claims the ship being filmed was carrying 120 barrels of radioactive waste when he alleged he used explosives to sink it some 32 kilometres off the Calabrian coast in 1992.

Investigators have long looked into claims that Italy's southern-based crime syndicates, including the Naples-area Camorra and the 'Ndrangheta ran illegal rackets disposing of toxic wastes, including in clandestine land dumps.

The plot of the Italian hit movie Gomorrah revolved around a Camorra racket that dumped toxic refuse in farmland near Naples.

Greenpeace and the Italian environmental group Lega Ambiente have been compiling lists over the last few decades of ships that have disappeared off Italy and Greece as they pursue reports of boats laden with toxic substances being sunk.

A Greenpeace official, Alessandro Gianni, told Associated Press Television News in an interview Tuesday that in the 1990s, his organization tried to learn the fate of ships that might have been involved in toxic dumping.