The incident alarmed Italy's Environment Minister Altero Matteoli, who described it as "serious" and said he had alerted Italy's environmental protection agency immediately on being informed of the incident, which happened October 25.

"Luckily, the first reports reaching us are that there has been no environmental consequences," Matteoli told reporters on the sidelines of a UN conference on protecting the Mediterranean here.

Captain Greg Parker and Commander Christopher Van Meter "were both relieved of their command," a Sixth Fleet spokeswoman told AFP. She would neither confirm nor deny that the sub was carrying nuclear weapons.

"Attack submarines do not generally deploy with nuclear weapons," she said.

Van Meter was captain of the nuclear-powered Los Angeles class sub when it grounded near the island of Caprera, north of Sardinia in circumstances which the navy said were still being investigated.

Parker was commander of the US navy's Submarine Squad 22 based in La Maddallena, Italy, and was on board the vessel at the time.

The disciplinary measures were decided after an investigation by the commander of the US Navy's submarine group based in Naples, the spokeswoman, Commander Kate Meuller, told AFP by telephone from Naples.

She said Admiral Stephen Stanley took the decision "after he lost confidence in their ability to command," said Meuller.

Meuller said three other officers from the submarine and three enlisted men were charged with dereliction of duty and disciplined in a "non-judicial proceeding," she said.

The sub suffered damage to the rudder and scrapes along its bottom, but Mueller insisted "there was no danger from the submarine to anyone or to the environment. There was no effect on the (nuclear) propulsion system at all."

"We were very certain from immediately that there was no breach of the sub's watertight integrity," she added.

WAR.WIRE