The shootings at two mosques in New Zealand, which left 50 people dead and dozens wounded, have led to renewed questions about the extent of far-right extremism.
The British security minister has said it is "perfectly possible" a far-right attack could happen in the UK and has raised concerns about the radicalisation of individuals online.
So, how widespread is this form of violent extremism?
Before the latest attack, both New Zealand and Australia said their main security risk was from Islamist terrorism.
And New Zealand's Security Intelligence Service's most recent annual report makes no reference to far-right extremism.
A report in 2017 by Australia's Security Intelligence Organisation says that although the country "experiences low levels of communal violence", one person was charged with far-right terrorism in 2016.
The report did not dismiss the possibility of attacks but stated that any attacks by far-right extremists would "probably target the Muslim or left-wing community, be low-capability, and be more likely to be perpetrated by a lone actor or small group on the periphery of organised groups".
Europol, the European Union's law enforcement agency, recorded five right-wing terror plots in 2017, all of which were in the UK.
This was out of a total of 205 potential or successful attacks recorded by European intelligence agencies, with 137 "separatist", 24 "left-wing" and 33 "jihadist" plots among them.
In 2017, a total of 1,219 terror suspects were arrested. Of these, 20 were classified as far-right extremists (705 were "jihadists").
The Global Terrorism Index, an annual report compiled from an open-source database at the University of Maryland, also monitors incidents relating to the far-right in Western Europe.
Its number of right-wing terror "incidents" is higher than the official figures from intelligence agencies, which it says is down to differing interpretations between countries as to what constitutes a terror incident.
Across Western Europe, the database shows 28 right-wing terror incidents in 2017 compared with just one in 2007.
Sara Khan, the UK's anti-terror commissioner, told the Observer that UK-based far-right activists were "organised, professional and actively attempting to recruit", although the numbers being monitored were not released.
The intelligence agencies have revealed, however, that of the 18 attacks foiled in the UK since March 2017, four came from the extreme right wing.
And referrals to the government's anti-extremism programme, Prevent, from this group have increased in recent years.
In 2017-18, there were 7,318 referrals across the country, 1,312 of which related to the extreme right.
The number actually going on to receive so-called "Channel" support has increased as well.
Since 2012-13, the number of extreme right wing individuals receiving support has almost tripled, while the number of Islamist extremists has increased by 80%.
In Germany, "politically motivated" crimes are recorded by the government
In 2017, 39,505 such offences were recorded, of which half were attributed to people with right-wing ideologies, including 1,130 acts of violence (although more acts of violence were attributed to the far left).
Right-wing individuals also committed 300 attacks on asylum centres in 2017, although this was a two-thirds decrease from the previous year.
In the Netherlands, the Ministry of the Interior