U.S. and Italian scientists are warning the next eruption of Mount Vesuvius might be significantly more deadly than Italian authorities expect.

Current Italian plans call for the evacuation of as many as 600,000 people from Naples, but the researchers say as many as 3 million people might be at risk.

Vesuvius is best known for its eruption in 79 A.D. that destroyed the Roman city of Pompeii. Modern plans for the evacuation of Naples are based on a similar-sized eruption, the BBC reported Tuesday.

But the scientists say there was even a greater Vesuvius eruption about 3,780 years ago which produced lava flows extending about 16 miles northwest of the volcano -- over and well past modern Naples.

Ruins of an ancient Pompeii temple

The co-author of the study, Michael Sheridan of the University of Buffalo, said the pattern has been a monstrous eruption of Vesuvius every 2,000 to 3,000 years -- and it's been 2,000 years since the last one.

The study, led by Giuseppe Mastrolorenzo of the Vesuvius Observatory at the National Institute of Geophysics and Volcanology in Naples, appears in the Proceedings of the National Academy of Sciences

Copyright 2006 by United Press International