Tens of thousands of Italians under heavy police guard marched on Saturday through the city of Vicenza to protest against the expansion of a U.S. military base that has divided the centre-left government, Reuters reported. Leftists who last year voted for Prime Minister Romano Prodi, an Iraq war opponent, turned out in droves to decry his approval for U.S. plans to expand the military base in Vicenza, home to the 173rd Airborne Brigade. Prodi appealed to demonstrators to refrain from violence, following warnings from the interior minister that the protest march which began shortly after 2 p.m. (1300 GMT) could attract people "hostile to the forces of law and order". The U.S. embassy had warned Americans to steer clear of the small northern Italian city of 115,000, where officials also shut schools normally open on Saturday as a precaution. But the protests were peaceful. Police estimates pegged the crowd at more than 50,000 people.