Hundreds of far-right nationalists, football fans and bikers have held a rally in central London to "protect" a war memorial, with some making Nazi salute gestures at police.
The protests on Saturday came after reports a Black Lives Matter demonstration was to take place at the city's national Whitehall Cenotaph memorial, which is to commemorate soldiers lost in war.
Videos posted to social media showed a heavy police presence at the event, with some protesters making Nazi salutes towards officers.
Only a small number of Black Lives Matter protesters arrived at the site.
Anti-racism protesters around the United Kingdom have prompted a heated debate about statues of controversial historic figures following the toppling of a Bristol statue of UK slave trader Edward Colston last week.
A statue of World War II Prime Minister Sir Winston Churchill was also defaced by anti-racism protesters.
Former Conservative minister Sir Nicholas Soames told the Daily Telegraph the incident, in which the word "racist" was scrawled on the monument, shows British society has "lost its compass".
People outside City Hall in Belfast in Northern Ireland to the protect war memorials in its grounds.. Source: Press Association
Sir Nicholas backed Prime Minister Boris Johnson's condemnation of disorder during last weekend's Black Lives Matter protests, and said London mayor Sadiq Khan was right to heed police advice and board up the statue and the nearby Cenotaph.
"I find it extraordinary that millions and millions of people all over the world who look up to Britain will be astonished that a statue of Churchill and the Cenotaph, our national war memorial, could have been defaced in this disgusting way," he told the Telegraph.
"These people who are marching did not set out to do this, but a very, very small, extremely explosive group of people who have made a practice of hijacking entirely responsible demonstrations are behaving in an unspeakable and cowardly manner.
"It feels like a society that has lost its compass."
Home Secretary Priti Patel told the Daily Mail on Saturday that Sir Winston was a hero of Britain "who fought fascism and racism in this country and Europe".
"He has given us the freedom to live our lives the way we do today," she said, adding that the decision to board up the statue was a "sad reflection" on Mr Khan's mayoralty.
"Had he (Mr Khan) called out the minority in particular who were subversive in a peaceful protest, and had he pulled up the thuggery in the right way, we would not be seeing the boarding up of our national hero."
Meanwhile, Sir Winston's granddaughter has told the BBC her grandfather's statue may need to be placed in a museum for safety.
Emma Soames said the war-time prime minister was a "complex man" but she was "shocked" to see his monument boarded up.
"It is extraordinarily sad that my grandfather, who was such a unifying figure in this country, appears to have become a sort of icon through being controversial," she said.
"We've come to this place where history is viewed only entirely through the prism of the present."
Additional reporting by AAP.