Terrorists are now more likely to be radicalised online but plots hatched on the internet are prone to fail, research suggests.

Academics examined the role the internet played in the radicalisation of 437 convicted extremist offenders in England and Wales in a study published by the Ministry of Justice (MoJ).

It said the internet is “increasingly prominent” in radicalisation but plots from attackers radicalised online were “most likely” to be foiled.

A third of the sample of criminals considered in the research had mental health problems or personality disorders. Conditions most commonly reported included Autism Spectrum Condition (ASC) and depression, with these “most common” among those mainly radicalised online, the findings indicated.

Analysis of specialist reports from 2010 to the end of last year also suggested the biggest increase in online radicalisation over time was among female offenders and people aged over 25, researchers said.

The report said: “Findings suggest that the internet has become increasingly prominent in radicalisation pathways and offending over time for convicted extremists in England and Wales.

“Technological advances have led to changes in the types of applications/platforms used over time.

“Mental health issues, neurodivergence and personality disorder/difficulties were relevant for a sizable proportion of the sample, with ASC, depression and personality disorder/difficulties recorded as the most common types of disorders, particularly for those who have primarily radicalised online.

“For attackers specifically, those exposed to online influences in their radicalisation pathway were more likely to use the online domain for attack planning behaviours …

“Those attackers reported as being primarily radicalised online were found to be the least successful in plotting attacks and most likely to see their plots foiled at the planning stage.”

The research was carried out by Nottingham Trent (NTU) and Bournemouth universities with the Prison and Probation Service and follows on from a report published last year.

Lead author Dr Jonathan Kenyon said the study provided a “contemporary picture” of the online activities of convicted extremists in England and Wales until the end of 2021 and found “marked differences” in behaviour and offending between those who were radicalised on the internet, in person or a mixture of both. This highlights the importance of taking these factors into account when “assessing risk” and considering how to tackle terrorism, he said.

Dr Jens Binder, associate professor of psychology at NTU’s School of Social Sciences, said mainstream websites and apps were “routinely” used, “sometimes to reach out to the many users there and to lead some of them to more secluded online locations” which is “likely to require a more pro-active and transparent approach from tech companies” so radical content is reported.

Dr Christopher Baker-Beall, senior lecturer in crisis and disaster management at the Bournemouth University Disaster Management Centre, stressed the findings were “not suggesting that those with mental illness represent a community from which terrorists are more likely to originate. Nor does the report suggest that mental illness be viewed as a predictor of terrorist intent. Instead, it highlights the importance of providing mental health support to those convicted of extremist offences to ensure they do not go on to reoffend or commit further acts of terrorism”.

The MoJ said the views expressed in the report are those of the authors and “are not necessarily shared” by the department, adding: “Nor do they represent Government policy”.