The UK terror threat level has been raised from “substantial” to “severe”, meaning an attack is thought to be “highly likely”.
Home secretary Priti Patel said the move was a “precautionary measure following the horrific events of the last week in France and last night in Austria”.
The decision was not based on any specific threat, she added.
Patel warned that the public should “remain vigilant” and report any suspicious activity to the police.
There are five terror threat levels in the UK:
- low - an attack is highly unlikely
- moderate - an attack is possible but not likely
- substantial - an attack is likely
- severe - an attack is highly likely
- critical - an attack is highly likely in the near future
According to the government, a threat level of severe means a terror attack is “highly likely”.
The decision to change the threat level, which was taken by the UK’s Joint Terrorism Analysis Centre, comes the day after four people were killed and 22 injured in a series of attacks in Vienna.
In a statement, Patel said the government’s most important duty was to “protect the British people”.
“We have already taken significant steps to amend our powers and strengthen the tools for dealing with the developing terrorist threats we face,” the government minister said.
“That process will continue, and the British public should be in no doubt that we will take the strongest possible action to protect our national security.
“As I’ve said before we face a real and serious threat in the UK from terrorism.
“I would ask the public to remain vigilant and to report any suspicious activity to the police.”
Assistant commissioner Neil Basu, who is the UK head of Counter Terrorism Policing, said there was “no intelligence” to link the attacks in Austria and France to the UK and the move to change the terror threat level was a precaution.
“Whilst we want the public to remain alert, they should not be alarmed by this change in threat level,” Basu said. “We have a variety of established operational tactics that are tried and tested, to ensure that the UK is both well prepared and protected from the threat of terrorism.”
He said that “established planning mechanisms” across the police service had been activated, which would lead to “enhanced protection and preparedness”.
“Some of this will be visible and involve additional police officers being deployed to certain places and locations, which the public can expect to see over the coming days,” Basu explained.
“From this afternoon we will begin to increase our levels of visible patrols and implement other security and protection measures.”