Moves to launch a private prosecution over Glasgow's bin lorry crash have been thrown out by Scotland's Lord Advocate.

Driver Harry Clarke, 58, from Baillieston was unconscious when the lorry veered out of control on December 22, 2014, killing six pedestrians in Glasgow City Centre.

Erin McQuade, 18, her grandparents Jack and Lorraine Sweeney as well as Gillian Ewing, 52, from Edinburgh and Jacqueline Morton, 51, and Stephenie Tait, 29, all died in the tragedy.

Relatives of Ms McQuade and her grandparents announced the decision to lodge a Bill of Criminal Letters last month - the first stage in launching a private prosecution against Mr Clarke - after an inquiry into their deaths found the incident might have been avoided if he had not lied about his history of blackouts.

A fatal accident inquiry held last year into the crash found Mr Clarke had "repeatedly lied in order to gain and retain jobs".

However the Crown Office publicly said Mr Clarke would not face criminal prosecution over the incident before the inquiry was held.

On Wednesday a Crown Office spokesman confirmed on Wednesday that Lord Advocate, Frank Mulholland, had also declined permission for the case to proceed.

He said: "The Lord Advocate has declined to grant concurrence to the bill for criminal letters seeking a private prosecution of the driver of the bin lorry involved in the George Square fatalities on Dec 22 2014.

"The original decision not to take criminal proceedings was made on the basis that there was insufficient evidence in law to prove that a crime had been committed and that position remains unchanged."

In the same announcement the Crown Office also confirmed a separate bid to launch an other private prosecution over another crash in Glasgow city centre had also been declined.

The families of two students who died after a driver blacked out at the wheel and careered on to a pavement had announced they were also launching a private prosecution.

Friends Mhairi Convy, 18 and Laura Stewart, 20, were walking on North Hanover Street in Glasgow on December 17, 2010 when a Range Rover lost control, mounted the kerb and hit them.

Driver William Payne, who was 50 at the time of the crash, was accused of causing death by driving while uninsured but charges against him were later dropped.

A fatal accident inquiry (FAI) into the deaths heard that in the three years before the crash, Mr Payne had suffered six blackouts.

A Crown Office spokesman said: "The Lord Advocate has declined to grant concurrence to the bill for criminal letters seeking a private prosecution of the driver of vehicle involved in the North Hanover Street fatalities on December 17th 2010.

"The original decision not to take criminal proceedings was made on the basis that there was insufficient evidence in law to prove that a crime had been committed and that position remains unchanged."

In both cases the families seeking private prosecutions still have leave to appeal the decisions to the High Court.