The UK’s terrorism threat level has been raised to severe, meaning an attack is “highly likely”, according to the government.
The announcement follows a meeting of the Cobra emergency committee chaired by Boris Johnson on Monday afternoon, and comes a day after a bomb was detonated outside Liverpool Women’s Hospital.
Speaking to reporters on Monday Priti Patel said the change was being made because two terror attacks had taken place within a month.
David Amess, a Conservative MP, was stabbed to death during a constituency surgery in Southend, Essex, on 15 October.
The home secretary said the Liverpool attack had had a “very significant impact across the community” and that her thoughts were with people in the city.
She added: “Alongside that, I want to give my personal thanks, and the thanks of the government, to our emergency services, the police in particular.
“I've been in touch with the chief constable, other emergency service workers as well, and our armed forces who've been part of the operational work that's on the ground.”
Britain’s terror threat level was only lowered from severe to substantial in February, at a time when the pace of extremist attacks in Europe had lessened.
Even so, Ms Patel said then, “terrorism remains one of the most direct and immediate risks to our national security”.
The Liverpool bombing took place just before 11am on Remembrance Sunday, when a taxi carrying one person pulled up to the Women’s Hospital in Crown Street.
David Perry, named locally as the car’s driver, has been hailed a hero for doing what he could to prevent harm coming to others. He was hurt in the attack but has since been released from hospital.
Four men have been arrested in connection with the bombing, the investigation of which is being led by counter-terror police with input from MI5.
Assistant Chief Constable Russ Jackson, of the northwest counter-terror police unit, told a press conference earlier on Monday the motive behind the attack was unclear.
He said: “Our inquiries indicate that an improvised explosive device has been manufactured and our assumption so far is that this was built by the passenger in the taxi.
“The reason why he then took it to the women's hospital is unknown.
“We are of course aware that there were Remembrance events just a short distance away from the hospital and that the ignition occurred shortly before 11am.
“We cannot at this time draw any connection with this but it is a line of inquiry we are pursuing.”
Register for free to continue reading
Registration is a free and easy way to support our truly independent journalism
By registering, you will also enjoy limited access to Premium articles, exclusive newsletters, commenting, and virtual events with our leading journalists
Already have an account? sign in
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies