Sir Keir Starmer has banned 11 foreign speakers from entering the UK ahead of Saturday's Unite the Kingdom march.
The rally, organised by Tommy Robinson, will be attended by around 50,000 participants this weekend.
The PM met police chiefs this morning ahead of the major policing operation summoned to cater for a number of busy events across the capital this weekend.
But Sir Keir has warned the "violent thugs who spew hatred on our streets" will be hit with the "full force of the law".
So far, 11 individuals, who were described as "foreign far-right agitators", have been barred from touching down in the UK ahead of the rally led by Mr Robinson, whose real name is Stephen Yaxley-Lennon.
Downing Street said the move was intended "to protect British communities from vile hate".
The PM said: "We’re in a fight for the soul of this country, and the Unite the Kingdom march this weekend is a stark reminder of exactly what we are up against. Its organisers are peddling hatred and division, plain and simple.
"We will block those coming into the UK who seek to incite hatred and violence."
The Prime Minister labelled the Robinson rally 'unpatriotic'
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One of those banned include US citizen and Republican candidate Valentina Gomez, who took to X to blast the "Orwellian" policing operation in place this weekend.
The Unite the Kingdom rally will be held at the same time as a pro-Palestine protest tomorrow in the heart of London.
Some 30,000 individuals are expected to descend on the city centre to attend the event to mark Nakba Day.
While the Metropolitan Police is set to use facial recognition at the Robinson rally, the same will not be applied at the neighbouring protest.
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The Unite the Kingdom march will take place tomorrow
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Scotland Yard added it would roll out the "highest degree of control" and the "most assertive use of our policing powers".
Authorities plan to deploy 4,000 officers to police a number of busy events across the capital.
Armoured vehicles will be on standby for the first time while every officer will be decked out with full riot gear ahead of Saturday.
In a statement today, Sir Keir added: "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.
"My Government will always champion peaceful protest but will act decisively against hatred.
"We all have a responsibility to speak out against those spouting vile divisive views wherever we see it.
"We are a country built on decency, fairness and respect, at our best when people from different backgrounds come together in common purpose.
"That is what we must fight for."