The incident occurred on Sunday, when a Libyan motor boat -- one of six Italy donated to Tripoli as part of the deal and with at least one Italian aboard -- fired with machine guns on a Sicilian boat with 10 men on board about 30 miles off the Libyan coast, according to Italian officials.

None of the fishermen was wounded, but the boat's captain recounted to Italian newspapers moments of terror as bullets ricocheted around the crew and said they were lucky to be alive.

Italian Interior Minister Roberto Maroni acknowledged the shooting should have been avoided and called it a "serious accident", but blamed it on a mistake.

"What happened the other day is something that should not have happened and Libya has apologised," he told Italian TV.

"Apparently there was an error of interpretation. Perhaps they mistook the fishing boat for a boat with illegal migrants."
He said he had ordered an investigation into the incident.

Italian officials have confirmed that there was at least one Italian aboard the Libyan boat when the shooting took place, but Maroni said they were there only as maintenance technicians and were not part of the boat crew.

Italian opposition politicians seized on the incident to attack Berlusconi's close relationship with Gaddafi, calling it the latest Libyan affront to Italy and demanded the government address the issue in parliament.

Gaddafi caused outrage among many in Italy last month when, during a trip to Rome, he urged hundreds of young Italian women to convert to Islam.