The disaster killed 140 people and caused major environmental damage.
A third vessel was involved in one of Italy's worst maritime accidents, according to a parliamentary inquiry.
The disaster, which happened in 1991, killed 140 people and caused major environmental damage.
A ferry, the Moby Prince, was heading to Sardinia when it collided with an anchored oil ship, the Agip Abruzzo, off the coast of Livorno.
Crude oil spilt into the sea and onto the ferry’s deck, sparking a huge blaze. Only one person on the ferry survived, while all the tanker’s crew were rescued.
Now a report has revealed an unidentified third vessel was involved.
"The Moby Prince collided with the Agip Abruzzo oil tanker because of the presence of a third ship that suddenly appeared before the ferry, provoking the left turn that caused the accident," the report said.
The probe into the Moby Prince disaster was reopened by Italy’s parliament in July last year. The decision to do so was taken when legislators realised the initial investigations conducted in the immediate aftermath of the incident did not identify its exact causes, nor result in any convictions.