The ferry has been moved to a shipyard for repairs

The Sea Express One, travelling from the Isle of Man, collided with the Alaska Rainbow in fog, close to the Alfred Dock in Liverpool.

The Marine Accident Investigation Branch (MAIB) completed a preliminary inquiry into the crash on 3 February.

It said a full investigation was needed to properly look into the cause of the collision.

None of 294 passengers on board the Isle of Man Steam Packet Company vessel were injured.

Services suspended

An operation was launched to pump water from the ferry as it started to sink into the Mersey. It is now at a shipyard in Birkenhead for repairs.

The Steam Packet's services between Liverpool and the Isle of Man are still suspended while a suitable replacement vessel is found.

The MAIB said in a statement: "Having completed a preliminary examination of the circumstances surrounding the collision between Sea Express One and Alaska Rainbow on 3 February 2007, the MAIB has now launched a full investigation.

"The collision occurred in fog and caused serious structural damage and flooding to Sea Express One, a high-speed passenger ferry on a regular service between Liverpool and the Isle of Man."