Police and UK intelligence services have foiled three terror attacks since the beginning of the coronavirus pandemic.
Counter Terrorism Policing disclosed the information as Home Office figures showed the number of arrests for terrorism-related activity fell by 34% in 2020, the lowest level in nine years.
Despite this, the number of terror plots prevented has risen to 28 since March 2017, police said.
Deputy Assistant Commissioner Dean Haydon, the senior national coordinator for Counter Terrorism Policing, said: “These statistics tell me two things.
“Firstly, that despite facing unprecedented challenges brought about by the pandemic, Counter Terrorism Policing continued to keep the public safe by making 185 arrests across more than 800 live investigations, stopping three possible terror attacks in the process.
“And secondly, that while the rest of us have been focused on protecting ourselves and our families from this terrible disease, terrorists have not stopped planning attacks or radicalising vulnerable people online.
“As we follow the Government’s road map out of the tightest restrictions there will be greater opportunity for terrorists to operate, and we want the public to join the police, security staff and retail workers in a collective community effort to minimise the chance of attack.
“We know from experience that public information and action helps save lives and lead to the significant arrests detailed in these statistics.”
The comments come as Foreign Secretary Dominic Raab told the Commons teenagers were being recruited to terrorist organisations during lockdown in “worrying” numbers.
He said: “In December 2020, the UK Counter-Terrorism Referral Unit saw a 7% rise in the volume of terrorist content online and we can see a worrying rise in the proportion of children and teenagers that are now being arrested for terrorism offences.”
Mr Haydon also warned that the data published on Thursday indicated a “worrying trend” was developing, with children under 18 being the only age category which saw an increase in arrests – rising from 12 in 2019 to 19 last year.
This accounted for 10% of all such arrests in 2020, up from 4% for the previous 12 months.
This was the highest proportion seen in an annual period, which the Home Office report said was “largely a result of falls in arrests of those in older age groups”.
Mr Haydon said: “Unfortunately we are seeing increasing numbers of young people arrested in relation to terrorism.
“But it doesn’t have to be this way. Ideally we would identify when a young person is being led down the path towards terrorism activity and use the Prevent programme to try and put them on a different path.”
He urged families and friends to ask for help over concerning changes of behaviour in loved ones and use the recently launched www.actearly.uk website and helpline.