Protesters toting Palestinian flags gathered in Toronto on Saturday. (Colin McConnell/Canadian Press)

Demonstrations were held in cities around the world to protest Israel's military offensive against Hamas as Israeli ground troops entered the territory on Saturday.

In Canada, rallies were scheduled in Ottawa, Toronto, Winnipeg and Vancouver.

At least 1,000 people gathered in Dundas Square, in Toronto's central downtown business district.

Officers on foot, bicycle and horseback patrolled the area as demonstrators for and against Israel gathered on either side of Yonge Street.

The rally was passionate but peaceful as people shouted at each other from across the street.

In London, at least 10,000 people, many carrying Palestinian flags, marched past British Prime Minister Gordon Brown's Downing Street residence to a rally in Trafalgar Square.

Once marchers stopped outside Brown's residence, hundreds of them hurled shoes at the tall iron gates that block entry to the narrow road.

Shoe-throwing has become a popular gesture of protest and contempt since an Iraqi journalist tossed a pair at U.S. President George W. Bush in Baghdad last month.

Rallies also were held in other British cities — including Manchester, Liverpool and Glasgow — and across Europe.

Protests in Paris, Amsterdam, Rome and Berlin all drew thousands of people.

In Paris, police said 21,000 marched through the streets, shouting "We are all Palestinians" and "Israel assassin."

Later, about 500 of the protesters turned violent, throwing objects at police, burning Israeli flags, overturning and torching cars, and vandalizing several shops, police said.

Ten police officers were injured in the clashes and 20 protesters arrested, a Paris police spokeswoman said.

Angry protests continued for a second day in Turkey, where about 5,000 demonstrators shouted "killer Israel" in downtown Ankara.

Thousands of people marched through Amsterdam, criticizing both the Israeli attacks and the Dutch government's failure to condemn them. One banner declared: "Anne Frank is turning in her grave. Oh Israel!"

More than 4,000 people demonstrated in Duesseldorf, Germany, and about 5,000 in Frankfurt.

Similar rallies were held In Berlin, Salzburg, Madrid, Oslo and Athens.

With files from the Associated Press