UK's terror threat level changed from 'severe' to 'substantial'

Britain's national terrorism threat level has been reduced to "substantial" from "severe" - the lowest it has been since 2014.

Home Secretary Priti Patel announced the move today as the country prepares for a General Election next month.

She said in a statement: "Despite the change in the threat level, terrorism remains one of the most direct and immediate risks to our national security."

It has been "severe" since September 2017, when the threat level was reduced from "critical".

It had been briefly raised following the Parsons Green Bombing on September 15, 2017.

Home Secretary Priti Patel said the threat level has been lowered (PA Wire/PA Images)

The "substantial" threat level continued to indicate a high level of threat, and an attack might well occur without further warning, the Home Secretary said.

The level is set by the Joint Terrorism Analysis Centre (JTAC), which weighs up available intelligence and the capability of known terrorist groups.

"Substantial" still means an attack is likely, according to MI5 guidelines.

It is the lowest the threat level has been since August 2014.

The threat level has been reduced to 'substantial' (AFP/Getty Images)

MI5 guidelines state: "Threat levels in themselves do not require specific responses from the public.

"They are a tool for security practitioners working across different sectors of the Critical National Infrastructure (CNI) and the police to use in determining what protective security response may be required.

"Vigilance is vital regardless of the current national threat level. It is especially important given the current national threat.

"Sharing national threat levels with the general public keeps everyone informed. It explains the context for the various security measures (for example airport security or bag searches) which we may encounter in our daily lives."