ROME - Bitterly cold weather gripped parts of Europe causing travel chaos on Monday, and a rare snowstorm in Rome prompted Italian authorities to call in the army to help clear the streets.

A Siberian weather system British forecasters dubbed the "beast from the east" brought snow, strong winds and the coldest temperatures for years to many regions.

The freeze was expected to continue for much of the week, and the World Meteorological Organization said daily minimum temperatures below 0 C were expected even in southern Europe.

"This cold period... could be a risk to life for vulnerable people exposed to the cold," it said.

Piazza Venezia, Rome's central square which is usually a cacophony of car horns and a tangle of traffic, was eerily empty, quiet and white as dawn broke.

In St. Peter's Square, priests and seminarians from the Vatican threw snowballs at each other.

It was the heaviest snowfall in Rome in six years and the largest for the end of February in decades.

Schools were ordered shut and many people could not reach their work. Police asked residents to stay at home if possible.

Rome's Fiumicino airport was forced to operate with only one runway during the night, when 10 centimeters of snow fell in less than four hours. The capital's second airport, Ciampino, was closed overnight and workers were clearing its two runways.

The weather brought chaos to Italy's rail network. Most express trains heading north from Rome and Naples faced at least three hours of delays.

The chill engulfed much of the country, with the harshest temperatures recorded in the Alps in the Valle d'Aosta, where a low of -34.9 C was recorded early on Monday.

Temperatures in Brussels are set to fall to as low as -10 C in the coming week, with strong winds adding a further chill factor. It is estimated that there are more than 3,000 homeless people in the Brussels region.

In Germany, temperatures plunged to their lowest so far this winter with a low of-27.5 C recorded at the Zugspitze, Germany's highest mountain.

More than 200 trains and over 60 flights were canceled due to the weather in Britain, where authorities said the country faced the coldest period for a number of years, with forecasts of snow and temperatures falling to-8 C.

Reuters - AP - Xinhua