Thousands of people rallied on Saturday in London and other UK cities for pro-Palestinian demonstrations and solidarity with Gaza, amid police warnings that anyone showing support for Hamas could face arrest.
Demonstrators marching through the heart of the British capital were shadowed by a heavy police presence of more than 1,000 officers.
Similar rallies took place in Manchester in northern England, the Scottish capital Edinburgh and other cities.
In London, demonstrators massed neared BBC News' headquarters before an afternoon rally near Prime Minister Rishi Sunak's Downing Street office and residence.
Parts of the entrance to the building in central London's Portland Place, where the rally started, were left splattered with red paint thrown by protesters from the Palestine Action group.
Some held Palestinian flags and placards - bearing slogans such as "Freedom for Palestine", "End the massacre" and "Sanctions for Israel". Chants of "Rishi Sunak, shame on you" could be heard.
"I think all just people around the world, not just in Britain, must stand up and call for this madness (to end)," Ismail Patel, chairman of the Friends of Al-Aqsa campaign, told AFP at the demonstration in the capital.
"Otherwise, in the next few days, (we) might see a catastrophe unfolding."
The rallies come as Israel has been relentlessly pounding the Gaza Strip and deploying tens of thousands of soldiers nearby ahead of an expected ground offensive, while ordering residents of northern Gaza to evacuate southwards.
The order has been met by condemnation from rights group, due to the density of the Strip with hospitals collapsing.
Israel's war on Gaza, which has now entered its eight day, and killed at least 2,200 people, injuring over 8,700. Hundreds of thousands of people are currently displaced, by the entire territory is faced with a complete blockade, completely cutting off water, fuel and food.
Ahead of the London protest, the city's Metropolitan Police Service said it would deploy more than 1,000 officers, as the events thousands of miles away reverberate in Britain and elsewhere.
On Saturday evening, they said in a statement that they had made seven arrests.
The Met said this week that general expressions of support for Palestinians, including flying the Palestinian flag, were not criminal offences but reiterated that supporting Hamas, who is designated by the UK as a terrorist group, was a crime.
Ferouza Namaz, 34, a student from Uzbekistan, joined the London protest, stressing that civilians in Gaza were "absolutely innocent".
"Just being Palestinian does not give the rights to kill them. These appalling atrocities have been taking place for so many years," he added.
Ben Jamal, director of the Palestine Solidarity Campaign, which called the march, told AFP it was designed to send a message to politicians who, he said, had "given the green light to Israel to commit war crimes".
Israel insists it does not deliberately target civilians in the Gaza Strip or other Palestinian territories, however, over 2,000 have been killed in the besieged enclave along this week. In the West Bank, over 250 Palestinians have been killed this year.
Over 20 have been killed this week in the occupied territory, during Gaza demonstrations.
Jeremy Corbyn, ex-leader of the main opposition Labour party addressed the London rally.
"If you believe in international law, if you believe in human rights, then you must condemn what is happening now in Gaza by the Israeli army," the now-independent lawmaker said.