Ten people have been arrested for public order offences after clashes at a protest near the Israeli embassy in London against air raids on Gaza.
Police said up to 700 people joined the demonstration and nearby Kensington High Street was closed to traffic.
The protesters resisted and threw placards when officers forcibly moved them back so that the road could be reopened.
The UK government has urged an "immediate halt" to violence in Gaza.
The protesters had gathered to wave placards, banners and flags bearing slogans such as "End the Siege in Gaza" and "Free Palestine".
Among them was 68-year-old Gamal Hamed, from Hammersmith, west London, whose 23-year-old son lives in Gaza.
"Yesterday was the bloodiest day in my homeland's history," he said. "We will do what we can to make the world take notice.
Some protesters were seen attempting to climb the gate towards the embassy and also throwing red liquid - to symbolise blood - towards the gate.
The clashes began after a small group of protesters stormed a barrier that had been penning them in.
Riot police were brought in to control the crowds and demonstrators were seen being handcuffed and taken away by officers as they tried to clear the street.
Several protesters left the scene with bloodied faces, according to a reporter from the Press Association.
The crowd chanted "shame on you" at officers as they were moved back from the embassy on Palace Green to Kensington High Street.
Campaigners said protests would continue on Monday.
Foreign Secretary David Miliband has called for an urgent ceasefire in Gaza after Israeli airstrikes left hundreds dead.
He said a recent rise in rocket attacks against Israel and the "massive loss of life" from the Israeli bombings made it a "dangerous moment".
"The deteriorating humanitarian situation is deeply disturbing," he added.
Mr Miliband said Prime Minister Gordon Brown had spoken his Israeli counterpart Ehud Olmert and made it clear Israel must stick by its humanitarian obligations.
International Development Secretary Douglas Alexander said the amount of aid needed in Gaza was "enormous".
"I note statements by the government of Israel that it wishes to avoid a humanitarian crisis, and its willingness to assist by opening one of the crossings into Gaza for limited humanitarian supplies today," he said.
He added: "Rocket attacks out of Gaza into Israel are indefensible and hampering efforts to help."
Conservative leader David Cameron called the violence "horrific" and said both sides must show "restraint".
Liberal Democrat foreign affairs spokesman Ed Davey described the strikes as "disproportionate" and "unacceptable".
The demonstration outside the embassy was organised by the Stop the War Coalition and Respect MP George Galloway and former Labour MP Tony Benn were among those who addressed the crowd.
Afterwards Mr Galloway said: "The support at today's demonstration has been overwhelming. There are even Jewish rabbis who have joined us here.
"We should treat Israel as we treated South Africa during apartheid. They should be shunned."
One of the event's organisers, Ghada Razuki, said she was pleased with the turnout.
"I hope that events like today's show that there is hope for Palestinians - I really hope they see it," she said.
Israeli jets have launched a second day of air attacks on the Gaza Strip amid warnings that operations will continue until Hamas ends rocket fire from Gaza.
Palestinians say at least 280 people have died in the air raids.
The UN Security Council has called for an end to all violence, including rocket attacks from Gaza.
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