British armed forces are guarding 12 sites in Scotland following the increased terrorism threat, the First Minister has announced.

The deployment comes as part of the first phase of Operation Temperer, which is being rolled out across the country by the UK Government.

The operation was called after the independent Joint Terrorism Analysis Centre raised the nation's threat level to "critical", meaning a terror attack can be expected imminently.

Soldiers have replaced armed officers from the Ministry of Defence's (MOD) police force and the Civil Nuclear Constabulary across the UK.

The three civil nuclear sites now under guard from members of the armed forces are Dounreay, Hunterston and Torness.

Nicola Sturgeon informed MSPs of the move on Wednesday.

She said: "Military personnel will be used at civil, nuclear and ministry of defence sites here in Scotland.

"There are a total of 12 such sites in Scotland; nine MOD and three nuclear."

Those armed police officers who are leaving their duties at the 12 sites will now create a contingency force which Police Scotland's chief constable Phil Gormley can call upon.

The First Minister informed the chamber that Police Scotland have no plans to use them at present but it will be kept "under review".

Scotland's national police force has around 600 armed officers.

The second phase of Operation Temperer involves military personnel being deployed on the streets.

Police Scotland currently have no plans to the request such a deployment.

Mr Gormley said: "Following the announcement by the Prime Minister of the UK Terror Threat level being increased from Severe to Critical and the implementation of Operation Temperer, Police Scotland is reviewing current deployments across Scotland, including of armed response vehicles and specialist firearms officers.

"As part of Operation Temperer, chief constables across the UK have the ability to request support from the armed forces, if required. This option is open to Police Scotland and the situation is being reviewed, however, the service currently has sufficient resources deployed and available at present."