Three alleged neo-Nazis have been arrested on suspicion of terror offences in coordinated raids across England.
The suspects are being interviewed by police as four properties in Bath, Leeds, London and Portsmouth are searched.
A spokesperson for Counter Terrorism Policing North East said: “The arrests were pre-planned and part of an ongoing investigation into extreme right-wing activity.”
The Independent understands that the trio are accused of being members of the Sonnenkrieg Division neo-Nazi group.
The organisation, which has online links to extremists in the US and Europe, promotes an ideology called the “universal order” that celebrates Adolf Hitler and Charles Manson.
Messages sent via a gaming server and seen by the BBC said police officers should be killed and called Prince Harry a “race traitor”.
The 17-year-old boy was arrested on suspicion of encouraging terrorism, disseminating terrorist publications and conspiracy to inspire racial and religious hatred.
The 18-year-old is accused of encouraging terrorism, disseminating terrorist publications.
The 21-year-old suspect was arrested on suspicion of possessing material likely to be useful to a person committing or preparing an act of terrorism, and conspiracy to inspire racial and religious hatred.
The operation came as new figures showed a record number of terrorist prisoners are being held in the UK.
Of the 224 people being held, 80 per cent were Islamists and 13 per cent were far-right extremists, while there were also other ideologies linked to Northern Ireland and those whose “beliefs are not clear”.
“The proportion of prisoners holding far-right ideologies has increased steadily over the past three years, with the number up from 16 to 28 in the latest year,” a Home Office document said.
White people have overtaken Asian suspects as the largest single ethnic group arrested on suspicion of terror offences in Britain.
In the year to September, 40 per cent of terror suspects arrested were white, 33 per cent were Asian, 12 per cent were black and 14 per cent were recorded as other.
“This was the second highest number of arrests of white people in a year since the data collection began in 2001,” the Home Office said.
“Arrests of persons of white ethnic appearance accounted for 40 per cent of arrests, an increase of five percentage points on the previous year.”
Of all suspects arrested in the year, 72 per cent were British nationals.
The number of children arrested under terror laws also increased slightly, with the number of under-18s detained up from 19 to 22. As in previous years, the 30 and over age group accounted for the most arrests.
Terror arrests fell by 31 per cent overall year-on-year, from 462 to 317, and the Home Office said the drop was caused by a rise in the wake of last year’s attacks in London and Manchester.
More than half of suspects were released without charge, a third were prosecuted, 5 per cent were released on bail pending further investigation and 6 per cent faced “alternative action”.
Police have launched waves of operations following the proscription of neo-Nazi terrorist group National Action, which became the first far-right group banned in the UK in December 2016.
Member Zack Davies tried to murder a Sikh man in “revenge” for Lee Rigby’s death in 2015.
Another National Action member plotted to behead an MP, while a serving soldier was recruiting for the group in the British Army.
Security services say they have foiled at least 13 Islamist and four far-right plots since the Westminster attack in March 2017 and terror investigations are at a record high.
Metropolitan Police Assistant Commissioner Neil Basu, the head of UK counterterror policing, warned in October that Islamists and the far-right were “feeding each other”.
“The overriding threat to the UK remains from those inspired by Isis and the resurgent al-Qaeda, but our operations reflect a much broader range of dangerous ideologies, including very disturbingly rising extreme right-wing activity,” he added.
MI5 are taking an increasing role gathering intelligence on far-right figures, having previously left the task to police while focusing on Islamists and international terrorist groups.
The government has called on technology firms to improve the detection and removal of anti-Islam, racist and neo-Nazi material on their platforms.
Pressure has increased after the Finsbury Park attack trial heard that Darren Osborne was radicalised in weeks by Facebook and Twitter posts by far-right figures.
The Counter-Terrorism Internet Referral Unit has reported a rise in the amount of extreme right-wing material being flagged.