Spectacular eruptions from the volcano on the southern Italian island of Stromboli may cause tidal waves, and all locals and tourists should stay away from the coast, emergency services said on Wednesday.

Two big lava flows burst out of Stromboli's side on Tuesday, sending up vast plumes of steam as they plunged into the Mediterranean waters below. Authorities said there was no immediate risk to people living on the island, off the coast of Sicily.

"The eruption (lava flows) are very well fed," said Enzo Boschi, head of Italy's National Institute of Geophysics and Vulcanology.

"But there's no reason to think that anything extraordinary will happen in the short term. The population is not at risk."

Locals fear a repeat of the events of December 2002 when a similar upsurge in volcanic activity caused a massive chunk of rock to drop into the sea, causing a 10-metre (33 foot) tidal wave that ruined houses close to the shore.

Emergency sirens sounded on the island when the new eruption began and local authorities ordered all residents to move to at least 10 metres above the water line.

The lava is flowing down an uninhabited part of the island and the risk, either of a greater eruption or of a tsunami, have not been deemed great enough to prompt a full-scale evacuation.

In winter only a few hundred people live on Stromboli, but the population swells to several thousand in the summer.

Tourists are drawn to climb to the 924 metre (3,000 ft) summit of the live volcano and peer down into its crater as the volcano blasts molten rock high into the sky.

The island was the setting for a 1950 movie starring Ingrid Bergman and in recent decades has, along with other islands in the Aeolian archipelago, become a favourite location for holiday homes for the rich and famous.

Designers Dolce & Gabbana, writer Umberto Eco and Italian President Giorgio Napolitano are all reported to have homes on Stromboli