POLICE are considering their operational response after the UK terror threat level was raised from substantial to severe.

The increase in threat level comes after an explosion outside Liverpool Women's Hospital on Remembrance Sunday.

Taxi driver David Perry survived the blast, but his passenger was killed when a homemade bomb exploded shortly before 11am.

The man, who is believed to have manufactured and brought the device into the taxi, died at the scene.

Police said the motivation for the attack was unclear, but it had been declared as a terrorist incident.

The Argus: Explosion outside Liverpool Women's Hospital on Remembrance Sunday Explosion outside Liverpool Women's Hospital on Remembrance Sunday

As a result, the Joint Terrorism Analysis Centre changed the threat level in the UK to severe on Monday afternoon.

Sussex Police say they are now “considering our operational response”, with ongoing discussions with Counter Terrorism Policing South East.

“The current threat level applies to the whole of the UK and not any specific area,” a Sussex Police spokesman said.

“While we want the public to remain alert, they should not be alarmed by this change in threat level.

“We ask for the public to work with us and remain vigilant. We appreciate calls from the public and we need communities to stand together and report any suspicious activity.

“If you see any suspicious activity, then please report it in confidence to police via the anti-terrorist hotline on 0800 789 321 or online at gov.uk/ACT.”

The rise in threat means an attack is “highly likely”.

Home Secretary Priti Patel said the threat level had been raised because the explosion in Liverpool was the second incident in a month.

The death of Conservative MP Sir David Amess, who was stabbed multiple times during a meeting with his constituents in Essex on October 15, was also treated as a terrorist incident by police.

Four men have been arrested in Liverpool under the Terrorism Act as part of the investigation into the recent explosion.

Prime Minister Boris Johnson, who chaired an emergency Cobra meeting earlier in response to the explosion, described it as a "sickening attack".

He said it was a "stark reminder for all of us to remain vigilant", but added "the British people will never be cowed by terrorism".