Thousands of anti-Israel demonstrators marched from Downing Street to the Israeli Embassy in west London on Saturday.
They were protesting against Israel’s action against the Gaza flotilla last week, when IDF commandos boarded the lead ship.
The “emergency national demonstration” was organised by groups including the Stop the War Coalition, Palestine Solidarity Campaign, British Muslim Initiative, CND, Friends of Al-Aqsa, Viva Palestina and Palestinian Forum of Britain.
They claimed more than 20,000 protesters had attended the London event, with busses bringing participants from around the country, but police put the number closer to 2,000.
Jonathan Sacerdoti attended as a spokesman for the Zionist Federation, but was forced to leave after being verbally abused by protesters.
He said: “I was at the Downing Street end of the protest. This was where the march was starting, and they had people addressing the crowd over a very loud PA system.
“As I was there doing TV interviews, it became clear to some people in the crowd that I didn't share their opinions, as they could hear some of what I was saying. As soon as we finished recording, one of them, accompanied by a few others, approached me and started to yell abuse at me.
“I left promptly. I did not see any violence or scuffles, but left as I would not have felt safe staying there.”
Around 3,000 protesters attended a similar march in Edinburgh, organised by the Scottish Palestine Solidarity Campaign.
Protests were also held in Leeds and Bradford and at other cities across the world including Los Angeles, Barcelona, Istanbul and Dublin.