Prime Minister raises terror threat level after Tube attack

Theresa May has confirmed that Britain's terror threat level has been raised to critical, the highest possible level, after an explosive device detonated at Parsons Green tube station in London.

Emergency services attending an incident at Parsons Green station. Picture: PA

The news came as it emerged that the so-called Islamic State terror network had claimed responsibility for the attack, which left 29 people with injuries, though none are serious or life-threatening.

With the perpetrator believed to still be at large, the threat level has been moved to critical from severe, which means that a terror attack is due to occur imminently.

It is the first time that the UK’s threat level has been at the highest level since the immediate aftermath of the suicide attack at Manchester Arena, which killed 22 people following a concert by the American popstar Ariana Grande.

The Prime Minister said military personnel would replace police officers “on guard duties at certain protected sites which are not accessible to the public”.

She said: “The public will see more armed police on the transport network and on our streets, providing extra protection.

“This is a proportionate and sensible step which will provide extra reassurance and protection while the investigation progresses.”