Mark Rowley said extremist propaganda and sexual abuse are ‘equally wicked’ forces for youngsters to be exposed to.

Children of convicted terrorists should be protected in the same way as those whose parents are paedophiles, one of the UK’s most senior police officers has said.

National counter-terrorism police chief Assistant Commissioner Mark Rowley said extremist propaganda and sexual abuse are “equally wicked” forces for youngsters to be exposed to.

He highlighted how parents are keeping care of their offspring even after they have committed terror-related crimes.

Mr Rowley also revealed for the first time that four far-right terror plots were foiled last year, as Britain faces a “significant” threat from “organised right-wing terrorism”.

In wide-ranging comments made ahead of his retirement next month, he:

– called for members of the so-called Beatles Islamic State cell to face justice, saying: “Locking them up and throwing away the key would be a great idea.”

– warned that far-right and Islamist extremists are feeding off each other to create a “toxic combination” that is helping fuel the terror threat;

– challenged internet firms to do more to help authorities tackle radicalisation and attack planning online;

– painted a stark picture of the scale of the challenge facing police and MI5, with more than 600 live investigations involving over 3,000 individuals of interest at any one time.

In a sweeping assessment of extremism and terrorism in Britain, Mr Rowley revealed that since the start of the conflict in Syria around 100 children have been safeguarded through the family courts.

He said: “The family courts and social services now routinely wrestle with child protection and safeguarding cases arising out of terrorism and extremism.

Tonight 6.30pm – Mark Rowley, UK Lead for Counter Terrorism Policing, will deliver his lecture "Extremism and Terrorism: The need for a whole society response" @Policy_Exchange You can watch the live stream here 📽️ ➡️https://t.co/cAj8FnhIdl pic.twitter.com/8q1oLiDqf5 — Terrorism Police UK (@TerrorismPolice) February 26, 2018

“However, we still see cases where parents convicted of terrorist-related offences, including radicalisers, retain care of their own children.

“I wonder if we need more parity between protecting children from paedophile and terrorist parents.”

Speaking to journalists ahead of a speech on Monday, he explained: “If you know parents are interested in sex with children, or if you know parents believe that people of their faith or their belief should hate everybody else and corrupt children for it, for me those are equally wicked environments to expose children to.”

Mr Rowley, who has led UK counter-terrorism policing for nearly four years, described the existing threat as acute, and called for a “whole society response”.

In a lecture at the Policy Exchange think tank, he warned of the “chronic threat” from extremism, saying: “It creates a fertile environment that allows the acute threat of terrorism to exist and thrive.

“I see extremists from Islamist and far-right persuasions both executing a common strategy.”

Mr Rowley, who oversaw the response to five terrorist attacks last year, is due to leave policing after a 31-year career within weeks.

Among those mooted as potential replacements are Assistant Commissioner Helen Ball and Deputy Assistant Commissioner Neil Basu, both from the Met; and West Midlands Chief Constable Dave Thompson.