Thousands of protesters have gathered in the Italian city of Florence for a series of anti-war and anti-globalisation events, amid fears of a repeat of the violence seen at the Genoa summit last year.

Some 20,000 protesters, mostly from Europe, are due to attend the 18 conferences, 140 seminars and 250 workshops and shows being held over the next four days.

There are fears the city's artistic treasures may be damaged

A major anti-war protest on Saturday is expected to attract some 100,000-150,000 demonstrators.

Billed as the European Social Forum, the Florence gathering is intended to mirror the World Social Forum that takes place in Porto Alegre, Brazil, each year.

Some 6,000 security forces are on hand and the authorities are enforcing strict border control to try to prevent extremist protesters from infiltrating the country.

Some two dozen people have already been turned away at the borders.

Italian authorities are worried about a repeat of the clashes during the Group of Eight summit in Genoa last year when a demonstrator was killed and hundreds injured.

Shops in central Florence have shuttered their glass-front windows, including those on the Ponte Vecchio bridge and McDonald's fast-food restaurants which have been a target of protesters.

Concerns

The Florence meeting was allowed to go ahead despite the government's concern that the city's artistic treasures could be damaged by demonstrators.

As a prelude to the Florence gathering, thousands of demonstrators descended on a US military base outside the nearby city of Pisa on Wednesday.

Close the shops. Close the restaurants, bars and markets

Italian columnist Oriana Fallaci

Helicopters hovered overhead and police in riot gear stood between protesters and the entrance to Camp Darby.

Protesters displayed banners saying "Drop Bush not Bombs!" and yelling "Yankees Go Home!".

"These are not wars against terrorism," protest organiser Piero Bernocchi of the Italian union group Cobas told the crowd.

"These are wars to dominate the world, and for oil and money, terrorism is just an excuse."