Tens of thousands marched through London calling for a halt to the bloody conflict in Gaza and a ban on U.K. arms exports to Israel. Protesters gathered beginning at noon Saturday at Whitehall, with estimates of the crowd ranging from 15,000 to 100,000.

The rallying point was at the Israeli Embassy in Knightsbridge. Speakers included George Galloway and Diane Abbott.

"Today's national demonstration will give people from across the country the chance to say enough is enough. Israel's siege of Gaza and its occupation of Palestinian land has to end now," Sarah Colborne, director of the Palestine Solidarity Campaign, said.

The march is being held as a public appeal for funds to help the victims of Israel's attacks on Gaza raise more than 4.5 million pounds ($7.55 million) in less than 24 hours.

Saleh Saeed, DEC chief executive, told the Guardian: "The funds are desperately needed, with ongoing fighting in Gaza creating an unbearable situation for families and children. Despite the end of the cease-fire, aid is getting through … but with the scale of the humanitarian crisis in Gaza, they urgently need more money to scale up their life-saving work."

Pressure group Peace Now called on supporters to rally Saturday night in Tel Aviv against the conflict and to call for a diplomatic solution.

Activists from various groups, including the Stop the War Coalition marched through London to a rally in Hyde Park.

Jeremy Corbyn, chairman of the Stop the War Coalition told the Voice of Russia, "The message we are giving to our government is two things. One, that there is a 8 billion pounds ($13.42 billion) trade between Britain and Israel in arms and related equipment, which ... should stop because of Israel's of behavior in Gaza.

"Secondly, the question of the European Union -- Israel trade agreement, which includes human rights clauses in it -- all of which have been breached by Israel -- and which is now under investigation for war crimes at the United Nations Human Rights Council."