The UK terror threat level has been reduced from critical to severe, British Prime Minister Theresa May said on Saturday (May 27).

The change means an attack is now highly likely, rather than expected imminently.

Confirming the downgrade on Sky News, May said: "I've just chaired a meeting of Cobra this morning where I've been updated by the police and the security services on the investigation into Monday's terrible attack in Manchester.

"A significant amount of police activity has taken place over the last 24 hours and there are now 11 suspects in custody.

"In light of these developments, JTAC – the independent Joint Terrorism Analysis Centre – has this morning taken the decision to reduce the threat level from critical to severe.

"The public should be clear about what this means. A threat level of severe means an attack is highly likely. The country should remain vigilant."

The change follows confirmation by Greater Manchester Police that two more men were arrested earlier on Saturday.

Police also evacuated Boscombe Street in Moss Side as bomb disposal squads were seen arriving on the scene.

Despite the reduction in threat level, May said that deployment of British troops in the streets would continue until the end of the bank holiday weekend.

"In recent days, members of the armed forces have been assisting police in providing reassurance to the public under Operation Temperer," May said.

"Today marks the start of a busy bank holiday weekend with many sporting events and other events taking place for which detailed security plans are already in place.

"To provide maximum reassurance to the public, Operation Temperer will continue to operate until the bank holiday concludes.

"Then on Monday, from midnight on Monday onwards, there will be a well-planned and gradual withdrawal of members of the armed forces who will return to normal duties."