Italy’s political opposition yesterday demanded an investigation after the wreck of a cargo vessel containing 120 barrels of potentially radioactive waste was found in waters off the southern province of Calabria. Environmental campaigners said that many more ships containing toxic and radioactive rubbish were believed to lie near by.

The discovery of the Cunsky, sunk in 1992, came after her location was revealed to anti-Mafia investigators by Francesco Fonti, a former member of the ’Ndrangheta, or Calabrian Mafia, who has become an informant. Mr Fonti claimed that the Cunsky contained radioactive material.

Mr Fonti has told police that he had used explosives to sink her and two other waste ships. The introduction of tighter European Union environmental legislation in the 1980s made illegal waste disposal a lucrative business for organised crime.

Investigators using a robot submersible filmed the Cunsky lying in 1,600ft of water nearly 20 miles off the coast. They said that the ship’s name was not visible, but it tallies with Mr Fonti’s information. The submersible recorded images of containers marked “toxic”.

Silvestro Greco, head of Calabria’s environment agency, said: “Even without taking into account investigations that suggest over 20 ships were sunk, the government must at least find these two other ships.” He said the presence of toxins and heavy metals in the Mediterranean was a matter of international concern.

Sebastiano Venneri, of the environmental group Legambiente, said that several former ’Ndrangheta members had confirmed that it had been paid to sink ships with radioactive material “over the past 20 years”.