Over 850 million images of motorists in Scotland are being held in a "gargantuan" police database, according to the Scottish Liberal Democrats.

A freedom of information request submitted by the party revealed that 852,507,524 number plate records logged by cameras, some dating back to 2009, remain on Police Scotland's files.

The database is compiled from 227 automatic number plate recognition (ANPR) cameras located across Scotland which can either be mobile or fixed.

The party's justice spokeswoman Alison McInnes said: "The figures acquired by Scottish Liberal Democrats have revealed Police Scotland's ANPR database is holding a gargantuan amount of data on innocent motorists.

"I find it disturbing the national force is now in possession of 850 million snapshots of people's journeys from the last seven years.

"ANPR cameras can be useful in locating stolen vehicles and identifying uninsured motorists but we've not been given any evidence to show just how effective they are at doing that.

"The overwhelming majority of these 850 million snapshots will belong to entirely innocent motorists and it is surely not proportionate or necessary to keep these for years on end."

Transport Scotland has previously stated that ANPR data collection is useful for tracking journey times between destinations, information which is then passed back on to motorists to help plan their routes.

Superintendent Jim Leslie, of Police Scotland's operational support division, said: "ANPR is a very useful tool in tacking criminality by serious and organised groups and terrorists, as well as in dealing with motoring offences, and a number of significant criminal prosecutions have been secured with evidence gained from using this technology.

"Data from ANPR is generally only available to Police Scotland officers for 90 days, and if required after this period a special case has to be made and approval given by an officer holding the rank of Superintendent or above."

An SNP spokesperson said: "The SNP is committed to a safe Scotland and we will continue to support Police Scotland and ensure that they have the resources they need to protect the people of Scotland by delivering an additional £100 million of investment over the next Parliament if re-elected."