A probe into the sinking of a bulk carrier which claimed 18 lives is to go to the highest level.

The loss of the 776-foot Leader L , which Bermuda was involved in as the closest point to the sinking, will be subject of an investigation by a top international shipping authority.

The move came after the tragedy caused outrage in shipping circles overseas and will bid to find out exactly what caused the 70,000 ton ship to sink in less than a minute.

For the first time ever, the International Association of Classification Societies (IACS) is to conduct its own inquiry into a sinking. It will run parallel to an inquiry already being handled by the flag state Panama.

The news came after the last of the survivors, who were brought to Bermuda after the disaster, finally departed the Island yesterday.

Lawyer Kelvin Hastings-Smith, acting for the ship's owners Leoninus Shipping Ltd., said: "The crew have all left. Everyone was reasonably happy. We hope the inquiry will continue elsewhere.'' A compensation deal has been settled with the 13 survivors who are Filipino, Romanian and Indian.

But two widows and one of the survivors have started legal action against the shipping company and the operators, Caro d'oro Shipping Ltd.

They are claiming damages in respect of the deaths of their husbands and injuries respectively.

Eighteen crewmen died when the Leader L sank 400 miles north east of Bermuda nearly two weeks ago. After reporting that one hold was taking on water, the situation deteriorated fast with the vessel sinking in less than a minute.

Survivors were picked from the sea by the Canadian Navy and brought to Bermuda along with six bodies recovered at the scene. The remainder of the 31 crew are believed to have gone down with the ship.

The IACS established a special casualty investigation board earlier this year and the Leader L will be the first case it has considered.

The inquiry is being undertaken at the same time the UK government ordered a new probe into the sinking of the largest British ship ever lost at sea.

A London-based judge will lead the inquiry into the loss of the MV Derbyshire which sank off Japan in 1980 with the loss of 44 lives.

As with the Leader L , "forces of nature'' or structural problems with the vessel were theories put forward as possible causes of the tragedy.

Inquiry planned: Survivors of the Leader L tragedy prepare to leave rescue ship HMCA Iroquois last month. An inquiry into why the bulk carrier took just one minute to sink with the lost of 18 lives is planned by a top international agency.