ROME, 26 June 2006 - A submerged island discovered off the coast of Sicily forms part of a vast underwater volcano, according to new research unveiled by Italian volcanologists.

Tracing two 40-metre columns of bubbles in the sea off the southern Italian island, researchers discovered smoking openings, the National Institute of Geophysics and Volcanology said on Thursday.

The smoke was coming from Fernandea, a submerged volcano which the researchers say may be as much as 30 kilometres long and 25 kilometres wide.

It has not been seen since it erupted in the 19th century. But the discovery of the volcanic outlets "is not a cause for concern", the institute's president Enzo Boschi said.

In 1831 an eruption caused Fernandea's peak to mount 65 metres above the surface of the sea, forming an island of volcanic matter of some four square kilometres.

Britain promptly claimed sovereignty over the new territory, naming it Graham Island, until the ruler of Naples and Sicily, King Ferdinand II of Bourbon, seized it and gave it its current Italian name.

France also briefly claimed control of the island, giving it the name Julia, but the matter became moot when the island sank again below the surface four months later.

Ferdinandea lies in Italian waters 30 kilometres off the coast of Sicily, between two other islands, Pantelleria and Lampedusa.

The Italian researchers gave the nickname Empedocles to their new volcanic discovery, after the ancient Greek philosopher. The Sicilian-born thinker is said in legend to have thrown himself into the volcano Mount Etna.