Thousands of pro-Palestinian protesters have begun marching in central London calling for an immediate ceasefire in Gaza.
The march, organised by the Palestine Solidarity Campaign, set off from Parliament Square shortly before 1pm and will pass through Whitehall before ending at Hyde Park.
Former Labour Party leader Jeremy Corbyn was among those holding banners at the front of the crowd.
Large numbers of Metropolitan Police could be seen around the square.
The pro-Palestinian march passed a fixed pro-Israeli demonstration on Pall Mall.
Part of the crowd stopped in front of the police cordon to display a banner.
Other protesters largely appeared to walk past the demonstration peacefully with chanting.
The group said it expects “hundreds of thousands of people” to attend the event in response to Israel’s “brutal attack” on Gaza.
A static demonstration organised by pro-Israel group Enough is Enough will take place at the same time in Pall Mall, along the route of the pro-Palestinian march.
The PSC is the 13th national protest since the first was staged on October 9.
The Met said these kinds of protests since October 7 had cost around £38.4 million and required 44,722 officer shifts as well as 6,399 officer rest days to be cancelled.
Assistant Commissioner Matt Twist said the force aimed to police “without fear or favour”, adding that protests in London had “been a particular cause of fear and uncertainty in Jewish communities”.
He said the events had caused some Jewish people to stay away from central London on protest days, avoid the Tube, hide their identities or otherwise change their behaviour.
A third demonstration organised by the Campaign Against Antisemitism (CAA) was due to take place on Saturday from 12pm until 2pm but was cancelled the day before.
The organisation said it cancelled the “walk together” event – expected to attract thousands of people – after receiving threats and identifying “hostile actors” who posed a risk to the safety of Jews.
Mr Twist added: “I know there are people who feel the solution is to see these protests banned.
“The bar for such a decision is incredibly high – it requires a risk of serious public disorder of the sort we simply haven’t seen either in this period of protest or for several years.”
The Met said each protest will be subject to conditions imposed under the Public Order Act limiting where protesters are allowed to go.
The PSC march must stick to a pre-agreed route via Whitehall, Piccadilly and Park Lane, the force added – as it stressed that areas in the vicinity of the Israeli Embassy, near Hyde Park, were not to be entered.
The smaller Enough is Enough demonstration is restricted to an area in Pall Mall.
Both protests must have concluded by 5pm, the Met said.
The now-cancelled CAA event had been arranged after the organisation’s founder, Gideon Falter, was threatened with arrest at a pro-Palestinian demonstration earlier this month, with one officer describing Mr Falter, who was wearing a kippah, as “openly Jewish”.
The Met said it understood the event may be held at a later date.
The force added 415 arrests had been made during protests – including 193 for antisemitic offences and 15 terrorism arrests, mostly for the alleged support of Hamas, which is a proscribed group in the UK.
Ben Jamal, director of the PSC, said the march was “fuelled by love for the principle of the dignity and rights of all human beings”.
He added: “As mass graves of Palestinians are uncovered in Gaza, the call for an immediate ceasefire and for an end to weapons sales to Israel is now supported across the political mainstream and by huge swathes of the British public.
“Those marching know that they are on the right side of history.”
