POLICE Scotland is planning to buy two drones equipped with high-resolution cameras in what would be a first for the force north of the border.

Tender documents reveal plans to spend around £125,000 on two “unmanned aerial vehicles” for the force's Air Support Unit, which currently consists of one helicopter.

Police Scotland said the drones would “greatly enhance” the unit’s ability to “quickly deploy resources to incidents such as missing person searches and crowd monitoring, obtaining live, detailed imaging of search areas and significantly reducing deployments”.

And it specified the machines should have a “minimum of six rotors”, alongside a tracking device, satellite positioning system and a high-definition camera capable of both daylight and thermal imaging.

But critics raised concerns over intrusion into privacy at a time of unprecedented CCTV coverage and data storage.

Green justice spokesman John Finnie MSP said: “I think the police have enough toys to be going on with at this time and I remain to be convinced that they need to add drones to their already excessively intrusive arsenal.

“Police Scotland already has access to an unprecedented level of information from CCTV systems and Automatic Number Plate Recognition sites.”

Tender documents posted to the Public Contracts Scotland website detail a raft of specifications for the drones, including “weather resistant and robust protective casing” to cope with Scotland’s climate.

The devices should also have a minimum flight time of 20 minutes, police said, as well as being “quick and easy to use”.

The force said the drones would be “deployed to units across Scotland for operational use, primarily in Aberdeen and Inverness”.

Assistant Chief Constable Bernard Higgins said “research is underway” to find a suitable drone.

He added: "Unmanned aerial vehicles will initially be deployed to the north of Scotland, to provide additional support to communities located in some of the most rural parts of the country, and within some of the country's most challenging terrain. Further information will be made public before these systems are put into operational use.

"These unmanned aerial vehicles will provide additional resources in the event the force helicopter is unable to travel due to inclement conditions.

“These systems will be used in a highly visible capacity to fulfil the force focus of keeping people safe and will be a valuable asset in protecting the most vulnerable members of society, including missing people.”

Earlier this year the first dedicated police drone unit was launched by Devon and Cornwall Police, with three full-time staff.