The UK's anti-radicalisation scheme has had a 50 per cent drop in referrals because of the coronavirus lockdown, officials claim.
The Prevent scheme was launched to monitor potential terrorist activity in the UK.
Experts are warning that terrorist groups could take advantage of the coronavirus chaos to move across Europe and plot attacks.
A key ISIS operative has already been apprehended in Spain and a terrorist cell was identified in Germany, leading to arrests.
There are also fears that extremists will target young people on lockdown with online propaganda.
Referrals to the scheme often come from teachers but during lockdown many youths are not at school or receiving support from officials.
Chief Supt Nik Adams, the national co-ordinator for Prevent, is concerned that youths spending more time online could be targeted.
"What concerns me greatly is that the decline in the number of referrals doesn't mean that there are fewer people that need our help, but that fewer people are able to access the support they need," Chief Supt Adams told The Guardian.
“Schools, mental health workers and other public services provide vital support and protection to young and vulnerable people.
"And the combination of those services being affected by Covid-19 and the fact people are spending more time online means a small number of vulnerable people are at greater risk of being drawn towards terrorist activity.”
The reduction in referrals is believed to be the largest drop since the programme was launched more than a decade ago.
Counter-terrorism monitors have seen a rise in extremist online hate speech.
ISIS is telling followers that the crisis could allow them to “overwhelm” the West while far-right extremists spread lies claiming that Muslims are breaking the lockdown.
“Isolation may exacerbate grievances that make people more vulnerable to radicalisation, such as financial insecurity or social alienation," Chief Supt Adams said.
“The extremists and radicalisers know this and, as ever, will look to exploit any opportunity to lead those people into harm, often using topical issues as hooks to lure them in.”
Last year six terrorist plots were thwarted in the UK.
