A huge police presence was deployed in London on Saturday two manage two opposing rallies, as well as football fans gathering for the FA Cup Final.
Tens of thousands attended a demonstration organised by far-right activist Tommy Robinson, while another several thousand people gathered to commemorate Nakba Day, which marks the expulsion of some 700,000 Palestinians during the creation of Israel in 1948.
Mustering in west London and ending with speeches near Piccadilly, it combined with an anti-fascism march organised by the Stand Up to Racism group.
Armoured vehicles, police horses, dogs, drones and helicopters were deployed along with at least 4,000 officers as the Metropolitan Police aims to avoid clashes.
London's Metropolitan Police said ahead of the duelling events that it would mount one of its largest operations in recent years.
As the marches progressed through the afternoon, police said they will be mindful of splinter groups coming in contact.
The marches took place at a particularly radicalised time in British politics, with parties on the far right and left advancing across the UK in local elections last week.
The Met has imposed various conditions on Saturday's two rallies, over their routes and timings, in a bid to keep rival attendees apart.
The force, which estimates the operation will cost £4.5 million (€5.1 million), warned it would adopt "a zero-tolerance approach".
That includes for the first time making organisers legally responsible for ensuring invited speakers do not break hate speech laws.
Meanwhile, police warned the FA Cup Final between Chelsea and Manchester City which kicked off on Saturday could strain the policing operation.
They voiced fears about football hooligan groups that have previously supported Robinson showing up.
As of mid-afternoon, police said 31 people had been arrested for a variety of offences.
“While this may seem high, to this point both protests have proceeded largely without significant incident," the Met said.
'Hatred and division'
Robinson, whose real name is Stephen Yaxley-Lennon, is a former football hooligan turned anti-Islam activist whose profile has soared in recent years, in particular online.
Last September, he drew up to 150,000 people into central London for a similarly themed rally proclaiming "national unity, free speech and Christian values" -- an unprecedented turnout for an event organised by a far-right figure.
He has tapped into growing public anger over tens of thousands of migrants crossing the English Channel each year in small boats, wider immigration policies, alleged free speech curbs and other issues.
Prime Minister Keir Starmer warned Friday that "anyone who sets out to wreak havoc on our streets, to intimidate or threaten anyone... can expect to face the full force of the law".
He accused the organisers of Robinson's rally of "peddling hatred and division".
Robinson has urged his attendees not to wear masks or drink excessive alcohol, and to be "peaceful and courteous".
The British government has also blocked 11 foreign nationals from entering the country for the “Unite the Kingdom” rally.
Right-wing figures claiming to have been barred include Polish politician Dominik Tarczynski, Belgian politician Filip Dewinter, anti-Islam commentator Valentina Gomez and Dutch activist Eva Vlaardingerbroek.
“We will block those coming into the UK who seek to incite hatred and violence," said Prime Minister Keir Starmer, who is fighting for his political life following those disastrous election results earlier this month.
"For anyone who sets out to wreak havoc on our streets, to intimidate or threaten anyone, you can expect to face the full force of the law.”
