Statistics obtained from the National Police Chief's Council under Freedom of Information show that just under half of individuals specifically vulnerable to Daesh-related radicalisation, and offered support from a Channel panel, refused to participate.
The figures from the last financial year (1 April 2015 to 31 March 2016) which were held by the NPCC showed that 245 individuals were offered by support by a Channel panel but 117 declined to date.
Channel is a goverment programme where a variety of agencies come together to offer early help to those vulnerable to all types of extremism.
However, refusal to take part does not mean that police end their engagement with those individuals.
A spokeswoman for the NPCC said: "Channel is just one of a range of intervention options open to police and partners, Where a person does refuse to participate in Channel – and of course, as a voluntary programme, this is their right – there will be continuing engagement with the individual concerned to seek alternative support measures.
"It should also be remembered that if anyone who has accepted or refused help goes on to become a national security threat, or commits an offence, they would be subject to a criminal investigation."
Anyone concerned that someone they know might be at risk of radicalisation should contact police on 101 for advice. Police work with a range of agencies to offer help and to safeguard those who are vulnerable.
More advice can be found by visiting www.preventtragedies.co.uk
Communications office
By phone: 0800 538 5058
By email: press.office@npcc.police.uk