Crowds have gathered in central London for a march led by right-wing activist Tommy Robinson.
Around 1,000 police officers have been deployed to the streets of the capital to “keep the peace” amid expected counter-demonstrations on Saturday.
Protesters could be seen filling the Strand wearing clothing and holding flags depicting the Union, English, Scottish and Welsh flags.
The crowd could be heard chanting “Rule Britannia”, “We want our country back” and Mr Robinson’s name.
One demonstrator was seen climbing on top of a phone box, while others held placards that read “Not far right, just right”.
Several Israeli flags were also being flown.
In a post shared on X ahead of the event, Mr Robinson, whose real name is Stephen Yaxley Lennon, said the protest would be “the biggest patriotic rally the UK has ever seen”.
His protest is set to move from the Royal Courts of Justice to a rally in Trafalgar Square.
A counter-protest by Stand Up To Racism and former Labour leader Jeremy Corbyn’s Peace & Justice Project is set to march from Russell Square and to a rally in Whitehall.
It is supported by the Trade Union Congress (TUC) and 11 trade unions, as well as groups such as Stop the War Coalition, Peace & Justice Project and Unite Against Fascism.
The police have already used powers under the Public Order Act to try to keep the opposing groups apart amid fears of serious disruption.
Chief Superintendent Colin Wingrove, who is in charge of this weekend’s operation, warned that police will “intervene decisively” to deal with protesters who break the strict conditions about when and where they are allowed to demonstrate.
He said: “Our first priority is to keep the peace to ensure that those exercising their right to lawful protest can do so safely.
“We have proactively used our powers under the Public Order Act to manage the timings and routes of marches and assemblies, ensuring that the groups are kept apart.
“Officers will intervene decisively to deal with any breaches of those conditions, prevent crime, and to respond to any other incidents.
“Everyone has a right to feel safe and be safe in London.
“Those who abuse the right to protest in an effort to unlawfully intimidate others or to use hate speech can expect to face police action.
“The police presence will be very visible and I would urge anyone out and about in London, whether participating in these events or not, to speak to an officer if they feel unsafe or wish to report an incident.”
A Trans Pride event, which includes a march from Langham Place to Wellington Arch where speeches will take place, is also being held on Saturday.
No conditions have been imposed in advance of the Trans Pride event, the police said.
By PA Reporters