The growing threat from “extreme right-wing” terrorism will be included in official threat-level warnings for the first time, the home secretary has announced.

Until now, the alerts – which tell the public if the risk is low, substantial or critical – have taken into account the threat of attack from Islamists only.

The change follows growing recognition of the rising threat from the far right, since the murder of 50 Muslims in Christchurch, New Zealand, in March.

In the same month, it emerged that four of the 18 terrorist plots that had been thwarted in the UK in the preceding three years had come from the far right.

Sajid Javid, the home secretary, said: “Our approach to stopping terrorists is the same, regardless of the twisted ideology that motivates them.

“While the Islamist threat remains, we have recently seen an increase in terrorist activity motivated by the extreme right wing.

New Zealand shootings: Victims of Christchurch mosque terror attacks Show all 11 1 /11 New Zealand shootings: Victims of Christchurch mosque terror attacks New Zealand shootings: Victims of Christchurch mosque terror attacks Zakaria Bhuiyan People gather hoping to find out information about Zakaria Bhuiyan who is still missing after the mosques shootings in Christchurch. David Moir/AFP New Zealand shootings: Victims of Christchurch mosque terror attacks Mucad Ibrahim Three-year-old Mucad Ibrahim, the youngest known victim of the mass shooting at two mosques in Christchurch, New Zealand, on 15 March 2019. Abdi Ibrahim via AP New Zealand shootings: Victims of Christchurch mosque terror attacks Nadeem Rasheed Nadeem Rasheed, brother of Pakistani Naeem Rashid who died alongside his son Talha Naeem, 21, who were killed in shooting at a Mosque in Christchurch, at their home town in Abbottabad, EPA New Zealand shootings: Victims of Christchurch mosque terror attacks Omar Nabi Omar Nabi speaks to the media about losing his father Haji Daoud Nabi, 71, in the mosque attack REUTERS New Zealand shootings: Victims of Christchurch mosque terror attacks Ash Mohammed Ash Mohammed, right, talks to a police officer about his father and two brothers who are missing near the Masjid Al Noor mosque AP New Zealand shootings: Victims of Christchurch mosque terror attacks Akhtar Khokhur Akhtar Khokhur, 58, shows a picture of her missing husband Mehaboobbhai Khokhar, 65. AP New Zealand shootings: Victims of Christchurch mosque terror attacks Wasseim Alsati A note is seen on a window of a door at the family home of Wasseim Alsati in Christchurch on 17 March 2019. AFP/Getty Images New Zealand shootings: Victims of Christchurch mosque terror attacks Haroon Mahmood Relatives offer condolences to nephew (centre) of Haroon Mahmood, a Pakistani citizen who was killed in Christchurch mosque shootings. AP New Zealand shootings: Victims of Christchurch mosque terror attacks Farid Ahmed Farid Ahmed (pictured) survived the Al Noor mosque shootings but his wife Husne was killed. AFP/Getty Images New Zealand shootings: Victims of Christchurch mosque terror attacks Syed Areeb Ahmed A relative shows a picture of Syed Areeb Ahmed, a Pakistani citizen who was killed the Christchurch mosque shooting. AP New Zealand shootings: Victims of Christchurch mosque terror attacks Naeem Rashid A relative looks at a picture on a mobile phone of Pakistani nationals Naeem Rashid and his son Talha Naeem (right) who died in the Christchurch shootings. AFP/Getty Images

“It is therefore important the public is properly informed about the threats we face, which is why we are making these changes.”

Mr Javid also announced a change to the definitions of the risk to “ensure clarity in the threat level system”.

Two further levels will be added – moderate, between low and substantial, and severe, between substantial and critical – to make five in total.

However, the additions do not affect the current threat level, which remains at severe – meaning “an attack is highly likely”.

Mr Javid said the inclusion of far-right terrorism had been recommended in an operational review by the Joint Terrorism Analysis Centre.

Until today, the threat level system described the threat from “international terrorism”, which had become largely synonymous with Islamist terrorism.

However, this is now seen as outdated for the further reason that Islamist terrorism can be home-grown, just as extreme right-wing terrorism can have an international dimension. Combatting far-right violence was once the responsibility of the police but top-level plots and suspects begin by being investigated by MI5, Britain’s domestic intelligence agency.

Of the 394 individuals who received support from the Channel programme, to counter potential violent extremism, in 2017-18, 44 per cent were referred for concerns related to right-wing extremism, and 45 per cent in respect of Islamist extremism.

As far back as March, Theresa May’s spokesman noted “a pattern of concern that the threat from the far right is on the rise”.

The new five-level threat warning system will be:

• critical – meaning an attack is highly likely in the near future;

• severe – meaning an attack is highly likely;

• substantial – meaning an attack is likely;

• moderate – meaning an attack is possible but not likely;