British diving instructor Dave Mallard yesterday capped off a revealing piece of research when he renamed the wreck formerly known as the Coralita, which lies 20 metres under the sea off Manoel Island.

Together with a group of experienced local divers, Mr Mallard set off with a bottle of champagne in hand to christen the X-131 Waterlighter which was used in the Gallipoli landings in 1915.

The X131 Waterlighter was one of 200 designed by Walter Pollock and Son of Faversham in Kent for the Dardenells (Gallipoli) campaign in 1915, one of the bloodiest battles of World War I. It stayed on in Malta as a water carrier until it was bombed in World War II while berthed in Grand Harbour and then scuttled in its current location.

For years, the wreck was thought to be an ordinary barge until Mr Mallard, an archaeological diver from the Isle of Wight, carried out an underwater survey and confirmed the vessel's historical significance. He alerted local diving instructor Tonio Anastasi and others who in turn informed the local authorities.

Mr Mallard yesterday sounded an appeal for the 30-metre-long wreck to be protected from the development of yachting facilities in the area as part of the Manoel Island project.

"The wreck has been on the charts for 40 to 50 years. Any development should have taken that into account. Now it has even more meaning since troops died on it in Gallipoli (Turkey). It is a monument to the Anzac troops and has more right to be on this site than any development."

The X-131 Waterlighter remains in almost perfect condition even though it is 100 years old and Mr Mallard believes it can remain like that for at least another century if steps are taken to protect it. The only other known surviving example is moored on the River Thames.

Mr Anastasi said that the Superintendent of Cultural Heritage had been informed together with the Malta Tourism Authority.

"The superintendence said it would be looking into the wreck and the general area. There are 200 years of history there as we often come across old bottles and clay pipes."

Documentary-maker Emi Farrugia, who was also on the dive, warned that the wreck could be lost forever unless steps were taken to protect it from development.

Martin Vella, from the Malta Marine Foundation, said: "This is a red-letter day for Malta. The wreck has gone from Cinderella and turned into a princess. Our aim is to protect these wrecks".

Mr Mallard said he had been informed that a wreck similar to Britain's historic Mary Rose - the only 16th century warship on display which was a firm favourite of King Henry VIII - was located beneath a quantity of silt at Kalkara Creek.