More than 170 people, believed to be English Defence League supporters, have been arrested following a remembrance service in Whitehall.
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.
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.
But police said there were no reports of disorder between opposing groups ahead of today's arrests.
Writing on Twitter, the Met's Public Order Branch said: "170+ supporters of EDL were arrested this p.m to prevent a breach of the peace. No reported disorder between opposing groups at this stage."
Attempts to avert disorder began earlier today when the force posted a string of messages on the micro-blogging site stating that any disruption to the two-minute silence would be "dealt with robustly".
And it warned that deliberately using abusive or insulting words or behaviour was an offence under the Public Order Act.
But its remarks were met with fury and prompted the force to issue a series of tweets to justify its position.
Human rights lawyer Jules Carey, of Tuckers Solicitors, wrote: "This is the kind of freedom the veterans died for."
Referring to Scotland Yard's threat to use rubber bullets if violence erupted at Wednesday's student march, he added: "Are the Met about to announce that rubber bullets have been authorised for use on anyone showing insufficient respect?"
The force insisted it had posted its warnings on the back of intelligence which suggested there could be a repeat of last year's scenes.
"Last year during the 2 min silence a group burnt poppies and a counter protest was also held. This caused considerable upset to the public," it wrote.
"Arrests were made in 2010 & 2 people were later convicted. Intelligence and info suggested a similar incident may occur this year.
"The tweets sent out from this account this morning were intended to warn against any similar protests taking place."
A source at the Red Lion said officers corralled 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.
"They did not want to go," he added.
"They resisted to the point they were throwing stools at the police and bar staff.
"It was not an average working day. The EDL decided to use this as a base. They were not happy that a number of our bar staff were not English."
Witnesses said the group was held outside the pub for several hours before being arrested.
There were no reports of injury in the fracas, which came after the EDL issued a statement on its websites warning members to conduct themselves "respectfully and responsibly" at the Westminster Armistice day service.
Referencing last year's disturbances, it said: "This is about the memories of the fallen past and present and anyone who acts otherwise will only be helping Mac in disrupting the day.
"We would ask that you refrain from alcohol consumption till after the day's proceedings have finished."
Tempers flared during the poppy burning incident in which Mac members were heard chanting "British soldiers burn in hell" before setting the symbol of remembrance alight during the two-minute silence.
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 today.
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.
As of today, supporting or being a member of Mac is a criminal offence.