LONDON — Tens of thousands of people demonstrated in European cities on Saturday against Israel's bombardment of Gaza, including protesters who hurled shoes at the tall iron gates outside the British prime minister's residence in London.

Amid increasing criticism of Israel, international diplomatic efforts are growing to end the strikes, which have killed more than 460 people and left 1,700 injured. Late Saturday, Israel launched a ground offensive, sending tanks and infantry into Gaza.

In London, at least 10,000 people, many carrying Palestinian flags, marched past Prime Minister Gordon Brown's Downing Street residence to a rally in Trafalgar Square. Outside Downing Street, hundreds of protesters stopped and threw shoes at the gates that block entry to the narrow road.

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

Police estimated the crowd in London at 10,000 to 12,000, but organizers said the number was much higher. The marchers included activist Bianca Jagger, ex-Eurythmics singer Annie Lennox and comedian Alexei Sayle.

"As a Jew, it's very moving to see so many people who are so outraged at Israel's actions," Sayle said. "Israel is a democratic country that is behaving like a terrorist organization."

After the rally, about 5,000 protesters marched on the Israeli Embassy in west London. Some youths burned Israeli flags and scuffled with police and hurled bottles and sticks at officers in riot gear. Several demonstrators were led away by police after leaping over metal barriers holding them back from the embassy.

Protest organizers accused police of charging into groups of demonstrators on the way to the embassy and said they would file a complaint.

In the United States, hundreds of protesters participated in a pro-Palestinian demonstration along New York's 42nd Street in front of Bryant Park.

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.