More than 170 people, believed to be English Defence League (EDL) supporters, have been arrested following a remembrance service.
The group was held outside the Red Lion pub in Westminster to “prevent a breach of the peace”, Scotland Yard said.
The arrests came around two hours after wreaths were laid at the Cenotaph to commemorate fallen servicemen, and millions of Britons held a two-minute silence to remember the nation’s war dead.
A source at the Red Lion said officers herded EDL members into the pub at around 11am in a bid to keep them in one place.
But he said elements within the group later became abusive towards staff, with some allegedly leaning over the counter to steal food.
Officers were called back to the premises at around 12.50pm and began to “physically push them out” of the drinking spot, he said.
“Some of the staff aren’t English and they were shouting at them, telling them to say ‘England is better than where I’m from’, and things like that,” he said.
Another source at the pub said rowdy scenes broke out as supporters were removed from the venue.
Witnesses said the group was held outside the pub for several hours before being arrested.
Trouble flared on Armistice Day last year when the far-right group clashed with Islamic protesters after members of Muslims Against Crusades (Mac) burned poppies outside the Royal Albert Hall.
The episode led to six EDL arrests including that of founder Stephen Lennon who was later charged with assaulting a police officer.
Mac had planned to hold a “Hell for Heroes” demonstration against Remembrance commemorations at the same site yesterday.
But the event was cancelled after Home Secretary Theresa May declared the hard-line group would join the likes of al-Qaida on a list of terrorist organisations banned in the UK.