Tens of thousands marched through central London yesterday to demand a ceasefire in Gaza with many also expressing fury at the UK government’s refusal to back one. As Israel ratcheted up its offensive in the coastal strip 2,200 miles away, around 100,000 people attended the latest demonstration – matching last Saturday’s record turnout for a pro-Palestinian march in the UK. One difference seemed to be a palpably more tense mood than previous marches, reflecting events unfolding in Gaza and widespread exasperation over the government’s approach to the three-week-old conflict. Before the protest, James Cleverly, the foreign secretary, prompted dismay by saying calls for a ceasefire “aren’t going to help the situation”. Among those on the march was company director Heff Morales, 56, who had come to register his disgust with the government. “For the first time in my life I’m ashamed to be British,” he said, “and I’ve been around a bit!” He added: “The UK’s general stance has been just terrible – the refusal to see that genocide is going on.” His wife, Nadia, also 56, was preoccupied with a topic that had seemingly angered many on the march: the decision of the UK to abstain on voting for Friday’s UN resolution urging an immediate “humanitarian truce” in Gaza. “They vetoed on backing a ceasefire – wow,” she said, shaking her head. Later, the former Labour leader Jeremy Corbyn addressed protesters in Parliament Square, saying: “It’s not much to ask, a ceasefire, when children are being killed by weapons coming through the rooms of their homes. “It is an eternal stain that the British government abstained on that vote.” Among the vast crowd, holding aloft a large Palestinian flag, Londoner Saad Mia, 47, maintained hope that another high turnout could influence the government. “The government represents us – it should be asking for a ceasefire,” she said. “It’s what the majority of people want.” Another factor at the forefront of protesters’ minds was the ongoing communications blackout from Gaza, which has made it close to impossible for most civilians to contact the outside world. Shazmin Naeem, 24, suspected the blackout was designed to hide Israeli war crimes. “Israel has the freedom to do whatever it wants as it tries to eliminate Palestinians. Journalists in Gaza who we’ve been following have disappeared, what’s going on is totally undocumented. We want the truth to be shown.” Her friend, Iqra Asim-Amin, 17, said: “It’s actually scarier to not know what’s actually going on.” Elsewhere, Helena Martins, 36, from south Brazil, said she was marching to register her disapproval at the unfolding destruction of Gaza. “They want to destroy everything. I’m here for humanity.” Throughout the march, stretching along the Victoria Embankment and on to Parliament, protesters repeatedly chanted “From the river to the sea, Palestine will be free”, despite controversy around the slogan’s meaning. The home secretary, Suella Braverman, has urged police chiefs to consider interpreting the chant as an “expression of a violent desire to see Israel erased from the world”. At about 2.30pm, tensions boiled over when police clashed with protesters close to Downing Street. Punches and kicks were thrown with officers ordering demonstrators to move away as they sought to assert control. Police later announced two arrests, one for assaulting an officer who was taken to hospital following the incident. Yet there was no repeat of scenes from last weekend when a protester was videoed chanting “jihad” at a smaller protest near the main march. On the eve of yesterday’s demonstration, the Met clarified that officers would now be expected to intervene if protesters chanted “jihad”.