A former mobster, Francesco Fonti, claimed that the 360ft-long ship is just one of dozens sunk by the Calabria-based 'Ndrangheta syndicate.
He told the authorities the vessel's name is the Cunsky and that he used explosives to sink it about 20 miles off Calabria in the south-west in 1992.
A robot submarine has been used to inspect a shipwreck in the Mediterranean which the Mafia turncoat claimed was sunk after being loaded with around 100 barrels of radioactive waste.
The authorities have so far been unable to detect a name on its hull, either because it was removed or is obscured by algae.
Fonti said he had been involved in sinking three vessels, and that the 'Ndrangheta made millions of pounds illegally dumping radioactive and other toxic waste from businesses in Italy and other parts of Europe.
A regional prosecutor, Bruno Giordano, said that if the exploration of the wreck does produce evidence of toxic waste, authorities will start a hunt for more sunken vessels. They believe there could be up to 32 in Italian waters.
The introduction of more stringent environmental legislation in the 1980s made illegal waste disposal a lucrative business for organised crime groups in Italy.
"The problem of ships loaded with radioactive waste and sunk deliberately is an Italian mystery that should have been resolved years ago," said Ermete Realacci, an opposition MP.
The environmental group Legambiente claimed yesterday (wed) that the mafia had also sailed some waste-laden ships to developing countries, including Somalia, disposing of them in exchange for giving automatic weapons to rebel groups.
"They were sunk off the coast of Somalia, or buried on land, around 1991 or 1992 in return for weapons from the 'Ndrangheta," said Sebastiano Venneri, the group's vice-president.
The 'Ndrangheta, an Italian mafia syndicate, has been accused by a former member of the gang of sinking dozens of ships loaded with toxic waste, much of it radioactive. He says a journalist and cameraman were killed to keep them from revealing the activity.

'Ndrangheta Italian mafia syndicate is centered in Calabria 
Turncoat Francesco Fonti has identified a wreck located a few months ago by environmental workers as MV ''Kunsky'' or ''Cunsky'' and says he sunk it himself in 1992, complete with 100 barrels of radioactive waste. The gang received £100,000 ($162,720) for the job.

The wreck was scoured last week by a robot, but could not be identified.  It lies 480 feet below sea level, and is about 330 to 360 feet long.  Its description and location have been found to match an old account Fonti gave authorities three years ago, and environmental detection equipment has been dispatched to the ship, images of which do show barrels in the area.

Fonti claims he blew it up with explosives from Holland and it was used to dispose of Norwegian nuclear waste. The damage seen by the team working at the site does appear consistent with this version of events. Prosecutors say it appears the issue is displaying "all the appearances of being a confirmation". Fonti says waste was disposed of for businesses across Europe.

Nicola Pace, an Italian prosecutor, said there was evidence of "deliberate sinking of 42 ships with cargoes of waste, including radioactive waste" but there has never been concrete proof. Investigators will seek more shipwrecks if the mystery vessel does indeed have a toxic cargo. Over thirty vessels are believed to be in Italian waters.

Both Fonti and environmental group Legambiente have also claimed vessels were sent to Somalia and other developing countries with toxic cargoes, which were either sunk with the ship or buried on land. Legambiente alleges that local rebel groups were given weapons in exchange for receiving the waste ships. Fonti claims that Italian TV journalist Ilaria Alpi's 1994 murder alongside her cameraman was because she had seen toxic waste arrive in Bosaso, Somalia.