Figures disclosed by the Ministry of Defence have revealed that 40 soldiers, sailors and air personnel have been referred to the terrorism prevention programme since 2019.
Half of the personnel were referred due to concerns about extreme right-wing activity, a Freedom of Information request submitted by The Times revealed.
This increased from five per year in 2019 and 2020 to 10 between January 2021 and April 2022.
However, The Times reported that the Government refused to disclose why the remaining 20 were referred to the anti-terrorism Prevent programme.
Other categories for referral include Northern Ireland-related terrorism and Islamic extremism.
An MOD spokesperson told the PA news agency that procedures are in place to report and rehabilitate those who are at risk of being drawn into extremism.
“Defence staff are prohibited from membership of proscribed organisations and personnel will be referred to the appropriate authorities if necessary,” he said.
“Our personnel are vetted upon enlistment. In all cases, we take early action to confront and challenge behaviours that fall short of the high standards expected. Our chain of command are vigilant and procedures are in place to report and rehabilitate those who are at risk of being drawn into extremism.”
It comes after a report by the Intelligence and Security Committee (ISC) in July found that extreme right-wing groups were targeting military personnel as potential recruits.
The report also found that leaders of the armed forces do not provide direction over whether the personnel can join the groups.
The committee said: “Extreme right-wing terrorists often display an interest in military culture, weaponry and the armed forces or law enforcement organisations – the director-general for MI5 noted that ‘many of these people are absolutely fixated with weaponry’.
“This leads both to individuals seeking to join the military, and groups seeking to recruit within the military.
“The fact that the armed forces do not provide clear direction to service personnel regarding membership of any organisation – let alone an extremist one – would appear to be something of an anomaly.
“It could be argued that this is a somewhat risky approach, given the sensitive roles of many service personnel.”