LONDON — Tens of thousands of people descended on Britain’s capital on Saturday in what is expected to be the country’s largest far-right rally in decades, organized by anti-immigration activist Tommy Robinson.

The “Unite the Kingdom” rally comes amid a surge of nationalism in the U.K., a far-right party topping the polls, and the murder of American conservative activist Charlie Kirk — an assassination Robinson has used to mobilize support in the run-up to the event.Robinson — whose real name is Stephen Yaxley-Lennon — has long inspired rallies of mostly white, mostly male followers shouting soccer-style chants against Islam and immigration.

He has billed the rally as Britain’s “largest free speech festival,” and posted a video on X Saturday morning of hundreds of people gathered in central London waving England’s flag and British Union Jacks.

Large crowds crossing Westminster Bridge toward the Houses of Parliament chanted: “Whose street? Our street,” and “The people united will never be defeated.” A group traveling from New Zealand also performed a haka, a ceremonial chanting dance of defiance that is a cherished cultural symbol of the country.

A crowd of Unite the Kingdom supporters attacked police officers with “projectiles,” police later said on X, adding that “a number of officers had been assaulted” as the group tried to enter a “sterile area” created to separate them from a smaller counterprotest organized by Stand Up to Racism.

Footage posted by the force showed police with riot shields pushing back a crowd of protesters.

Robinson had told attendees not to wear masks, drink alcohol or be violent.