The social media platform had been heavily criticised for allowing its official page, which had more than two million “likes”, to remain online after posts were linked to the Finsbury Park terror attack, murder of Jo Cox and a car ramming targeting Muslims.
Paul Golding and Jayda Fransen were jailed for religiously-aggravated harassment last week and had been banned from Twitter in December.
A spokesperson for Facebook said it did not remove pages “just because some people don’t like them” and allowed controversial political opinions.
“But political views can and should be expressed without hate,” a statement added.
“There are times though when legitimate political speech crosses the line and becomes hate speech designed to stir up hatred against groups in our society.”
Facebook said the official Britain First page and those of Golding and Fransen had repeatedly broken its community standards, sparking a written final warning that was also violated.
“As a result, in accordance with our policies, we have now removed the official Britain First Facebook page and the pages of the two leaders with immediate effect,” a spokesperson added.
“We do not do this lightly, but they have repeatedly posted content designed to incite animosity and hatred against minority groups, which disqualifies the pages from our service.”
Theresa May welcomed the announcement and said the Home Secretary was working with Facebook and other firms to ensure they do act more clearly in taking down material of an extremist nature.
“I’m very pleased to welcome the announcement that Facebook has made and I hope other companies will follow,” the Prime Minister told MPs.
Tell Mama, which records Islamophobic hate crime in the UK, said Facebook's decision was "long overdue", adding: "We will continue to work with Facebook to remove any back-up accounts linked to Britain First and its leadership."
It came after the Britain First leaders were jailed for anti-Muslim hate crimes after targeting people they wrongly believed were involved in an ongoing rape trial.
Fransen was sentenced to 36 weeks imprisonment and Golding for 18 weeks after the court heard that their actions could have caused rapists who gang-raped a teenage girl to walk free.
Judge Justin Barron said their words and actions “demonstrated hostility” towards Muslims and Islam, adding: “I have no doubt it was their joint intention to use the facts of the case for their own political ends.
“It was a campaign to draw attention to the race, religion and immigrant background of the defendants.”
Golding, 36, was convicted of one count of religiously aggravated harassment and acquitted on two others.
His deputy, 31-year-old Fransen, was found guilty of three counts of the same offence and cleared of one.
The court heard how she shouted racist abuse through one of the defendant’s doors, when his pregnant partner was home alone with their two young children.
Prosecutors said it was one of several incidents of Fransen and Golding “filming and harassing people” they incorrectly believed were involved in the trial, putting the footage online and posting offensive leaflets through letterboxes in Kent.
Britain First styles itself as a “patriotic political party” but is not registered with the Electoral Commission.
Founded in Swanley as a splinter group of the British National Party, members became known for launching so-called Christian patrols and mosque “invasions”, while campaigning against immigration and Islam.
Britain First has forged links with extreme nationalist movements across Europe, with Fransen attending a march in Poland where she called Islam a “cancer moving through Europe”, adding: “Our children are being bombed, our children are being groomed and our government does nothing.”
The Finsbury Park terror attacker, Darren Osborne, read Britain First posts while planning his attempted massacre of Muslim worshippers, while neo-Nazi Thomas Mair repeatedly shouted the group’s name while murdering Labour MP Jo Cox.
It is among the organisations perpetuating the idea of a cultural “war against Islam”, a report found, after police revealed that four far-right and 10 Islamist terror plots have been foiled in the last year.
Britain First’s largest following was on Facebook, where its official page put out a stream of unsubstantiated videos frequently claiming to show crimes committed by Muslims, alongside photos and memes.
Three videos posted from Fransen’s Twitter account in November were re-tweeted by Donald Trump, giving Britain First international notoriety and sparking a diplomatic row after Ms May condemned the action.
Weeks later, both Fransen and Golding were banned from Twitter in a crackdown on extremism and hate speech, leaving Facebook as the group's largest platform.
Britain First’s main website remains online, as does a YouTube channel that has more than 60,000 subscribers but no videos, and an email subscription service.
Fransen and Golding are due to stand trial in Northern Ireland next month over separate allegations of inciting hatred at the “Northern Ireland Against Terrorism” rally in Belfast.
But their imprisonment has thrown proceedings into doubt, with Belfast Magistrates' Court contacting English authorities to establish whether they can be brought to court from prison or appear by video-link.
Security services have been sounding mounting warnings over the danger posed by the far-right amid fears of “reciprocal radicalisation” between the group and Islamists.
Neo-Nazi group National Action became the first far-right organisation banned as a terrorist organisation by the British Government in 2016, sparking a wave of police crackdowns.
The Border Force has refused entry to three far-right figures in recent days.
Martin Sellner, the Austrian leader of pan-European “ethno-nationalist” movement Generation Identity was detained upon arrival at Luton Airport on Friday and deported over a planned speech at Speakers’ Corner that authorities said could incite tension in local communities.
His girlfriend Brittany Pettibone, an American alt-right activist, was also detained and deported for planning to film the speech and interview Tommy Robinson, whose posts were among those that inspired the Finsbury Park attack.
A Canadian activist, Lauren Southern, was prevented from entering the UK from Calais on Monday over the “distribution of racist material” in Luton.
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