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LONDON (Reuters) - Armed police will patrol trains across Britain from Thursday for the first time, British Transport Police said, after the terror threat level was raised to critical following a suicide bombing in Manchester on Monday.

The bomber killed 22 people in the attack on a concert hall in the northern English city. Members of the armed forces have been deployed at key sites to boost security since the threat was raised to its highest level for the first time in 10 years.

Armed officers have been regularly patrolling the London Underground since December last year, but this will be the first time they have will have patrolled on board train services elsewhere in the country, the police said.

“By having firearms officers on board trains we’re ensuring that trains remain as safe as possible for passengers. Our patrols will be highly visible and passengers should feel comforted by their presence,” British Transport Police Chief Constable Paul Crowther said in a statement.

Crowther said the move was not due to any specific intelligence related to trains but was part of the national plan to deal with the continuing threat.