A MAJOR counter-terrorism exercise will take place in the Scottish Borders and neighbouring districts from today.

A warning has been issued by the Home Office to expect additional emergency service vehicles on the roads during the large-scale exercise.

But exact details of Exercise Border Reiver are being kept secret until it reaches its conclusion on Thursday.

Police Scotland's assistant chief constable Bernard Higgins explained: "Police Scotland and other police forces throughout Britain regularly assess and exercise their counter terrorism resources and capabilities to ensure we can respond appropriately to any incidents, which may arise.

"Exercise Border Reiver is the culmination of months of planning with partner agencies from across the UK and the scenario that will unfold over the three days is a realistic, challenging and complex set of circumstances that could arise during a terrorist incident.

“In addition to uniformed officers, a range of specialist Police Scotland resources will be in play for the exercise and this will result in some significant activity within the public domain.

"Please rest assured this all forms part of the live-play scenario and there is no risk to the public.

“The public should be reassured that we are constantly testing and exercising our plans along with our partners.

"Police Scotland is committed to ensuring that Scotland is capable of responding to the terror threat that faces the UK.”

The exercise will begin near Edinburgh this morning and will continue at smaller sites and individual properties across Scotland and the North East of England until Thursday.

Over a year of preparation has gone into the exercise.

And most of the anti-terrorism scenarios will be played out inside cordoned off areas.

Northumbria Police assistant chief constable Darren Best added: "This exercise has been organised to test the response of the emergency services and other partner agencies to a cross-border incident.

"It is in no way linked to a specific or increased threat in our region.

"We regularly carry out exercises to test contingency plans and the co-ordination of the response to a major incident to ensure we are prepared to keep our communities safe.

"We want to reassure people the exercise will not affect day to day policing and emergency service response which will continue as usual throughout the exercise."