The number of people being flagged as potential extremists by members of the public has doubled in the wake of a string of terror attacks in Britain.
Police received around 200 referrals in July to Prevent, the Government's anti-terror scheme, compared to roughly 100 in the previous four months.
A spike in the number of tip-offs came after the UK was hit by a series of attacks, beginning on March 22, in Westminster, Manchester, London Bridge and Finsbury Park.
The level of referrals coming from members of the public still remains minimal, however, according to Prevent.
It has now called for more communities to engage with the scheme in a bid to prevent further atrocities.
Police Prevent teams receive around 20 calls a day with referrals from agencies and members of the public, figures show.
But of 6,300 calls in 2016/17, fewer than one in 10 originated from within communities.
Disclosing the latest figures, Simon Cole, the national policing lead for Prevent, questioned whether participation in the scheme should be made compulsory in some cases.
"We have recently seen the devastating effects of what can happen when radicalisation is allowed to fester unchecked," he said.
"On the one hand it is encouraging that more people are contacting police with their referrals.
"But if we are to successfully stop vulnerable people from being drawn into violent extremism, then family members, friends and community leaders must trust us sooner with their concerns.
"Not only will that possibly stop another lethal terrorist attack from taking place, but it will also potentially prevent vulnerable people from being drawn into criminal activity from which there is no coming back."
Thirty-six people were killed in the four terror attacks to have taken place on UK soil in 2017.
Meanwhile, Prevent has been credited with playing a role in disputing more than 150 attempted journeys to places such as Iraq and Syria.
The share of Prevent referrals relating to concerns about extreme right-wing ideology in the past months has doubled to around 15%, while 55% to 60% are linked to Islamist extremism.
On the issue of whether Prevent should be compulsory, Mr Cole said: "I think that's a really interesting question.
"What do you do with returners (from Syria)? Should they have to automatically go on a programme?
"There's a bit of me at the moment thinks the fact this is a voluntary scheme is a good thing.
"But I can accept there might be some categories of people for whom there is some compulsion and that needs linking into risk."