Three terror attacks have been prevented in the UK since the coronavirus pandemic began, according to security services.

Arrests for terrorism-related activity fell by 34% in 2020, the lowest level in nine years, Home Office data showed. But the number of terror plots stopped has risen to 28 since March 2017, counter terror police said.

A senior officer warned: «Terrorists have not stopped planning attacks or radicalising vulnerable people online.»

Deputy Assistant Commissioner Dean Haydon said officers had made «185 arrests across more than 800 live investigations – stopping three possible terror attacks in the process».

The senior national coordinator for Counter Terrorism Policing said that as lockdown eases «there will be greater opportunity for terrorists to operate». «We want the public to join the police, security staff and retail workers in a collective community effort to minimise the chance of attack,» he said.

In February, the UK’s terrorism threat level was downgraded from «severe» to «substantial», which means means an attack is still likely.

Mr Haydon also warned of a «worrying trend» of children under the age of 18 being arrested for terrorism-related activities. This age group was the only one that saw an increase – rising from 11 to 17 in total, Home Office data showed. «That is a total of 10% of all arrests, which has risen from just 4% in the previous 12 months,» said Mr Haydon.Police have launched a website and helpline to offer advice and support for families to prevent young people becoming involved in terrorism, he said.