The Home Secretary has approved a move to proscribe neo-Nazi group National Action, branding the organisation “racist, anti-Semitic, and homophobic”.

Membership of the fascist group will become a criminal offence on Friday, marking the first time a far-right organisation has been banned under terrorism laws.

The self-styled "nationalist youth movement" had expressed admiration for terrorist Thomas Mair, who murdered Labour MP Jo Cox in June, and tweeted offensive language about Jewish people lifted directly from Adolf Hitler's Nazi Party.

Amber Rudd said: “As Home Secretary, I am clear that the safety and security of our families, communities, and country comes first.

“National Action is a racist, anti-Semitic, and homophobic organisation which stirs up hatred, glorifies violence, and promotes a vile ideology, and I will not stand for it. It has absolutely no place in a Britain that works for everyone.”

National Action is the first organisation engaged in far-right activities to ever be proscribed in the UK.

Proscription makes it a criminal offence to belong to the organisation, arrange meetings in support of the group, or wear clothing or carry articles in public which appear to promote it.

Proscription offences carry a maximum sentence of 10 years in prison and an unlimited fine. Groups can also have their assets frozen.

Under the Terrorism Act 2000, the home secretary can proscribe any organisation she believes to be “concerned in terrorism”.

There are currently 70 organisations proscribed under the act. The majority are Islamist groups. A further 14 organisations in Northern Ireland were proscribed under previous legislation.

National Action has tweeted material appearing to glorify terrorist Mair in the past, including a photograph of the killer accompanied by the message: “VoteLeave, don’t let this man’s sacrifice go in vain. Jo Cox would have filled Yorkshire with more subhumans!”

Another read: “Only 649 MPs to go.”

The group has also altered its listing on Google to read: “Death to traitors, freedom for Britain!”, a slogan which echoes the phrase Mair said in court when asked to give his name soon after being charged with Ms Cox’s murder.

Mair received a life sentence for the killing when he was convicted last month. The 53-year-old, who was described by a court as having committed a terrorism offence, was revealed to have a Third Reich eagle monument, embellished with a swastika, and other Nazi paraphernalia in his bedroom, along with information on white supremacist neo-Nazi movements in the UK and abroad.

The Yorkshire branch of National Action has also been accused of seeking to incite the murder of Jewish people, including tweeting a derogatory term used by the Nazis to describe Jews during the holocaust: “Tykes gassin K#kes is our motto, #Yorkshire needs you #AntiCommunism #ProNationalSocialism #DefendBritain."

The groups Twitter account has now been suspended.

The move to ban the organisation coincides with the prime minister Theresa May's vow to tackle anti-Semitism in the UK, and the introduction of an expansive new official definition of anti-Jewish abuse.

National Action’s monthly update for November, posted on the group’s website, dismissed reports it could be proscribed as “below discussion on grounds of extreme ignorance”.

“We neither sanction or endorse terrorism,” it said. Today, MPs decided otherwise.

National Action is not unique in the UK. The North West Infidels said on social media the group believes Ms Cox “got what she deserved” because of her liberal views and pro-EU stance and urged supporters to “fight extremism with extremism”.

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People at risk from far-right indoctrination now account for 25 per cent of all cases receiving help from Channel, the official scheme for those deemed likely to engage in violent extremism.

The British government appears to be taking the threat posed by the far-right more seriously than in the past, leading to speculation other groups could be banned in the near future.