Half a million people have rallied in London against the far right, the demonstration's organisers claim.
The crowds came out for the Together Alliance event, which was framed as a stand against the "politics of division".
It comprised a march, speeches in Whitehall - including a video message from London Mayor, Sir Sadiq Khan - and a music event in Trafalgar Square.
A separate march organised by the Palestine Coalition also took place, joining the route of the Together Alliance march before the groups combined in Whitehall.
Elsewhere, 18 people staged a protest outside New Scotland Yard in support of Palestine Action, a proscribed organisation.
The Metropolitan Police announced on X, formerly Twitter, that 25 arrests have so far been made in all at both demonstrations -18 were for supporting Palestine Action, two were for climbing up the National Gallery columns and five for other offences.
It comes after more than 100,000 people turned out for a right-wing rally, Unite The Kingdom, in London last September.
That event, planned by right-wing activist Tommy Robinson, sparked several incidents of violent disorder which left some police officers injured.
In comparison, today's rally against the far right drew an estimated 500,000 people, co-organiser Kevin Courtney announced to the crowds on Whitehall.
He said: "Our estimate is now that there are half a million people on this demonstration - the biggest demonstration ever against the far right.
"And it gives us all confidence to carry on. Thank you very much."
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Another organiser, Sabby Dhalu, said: "We're confident that the size of our mobilisation here today has actually intimidated the far right.
"I think they are not confident enough to stand against us because they know that we're going to be out in big numbers."
(c) Sky News 2026: 'Half a million' join London rally against the far right, claim organisers
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