POLICE Scotland is facing possible health and safety charges over the M9 incident in which a couple lay in their crashed car for three days despite the alarm being raised with police.

A legal source said the Crown Office is considering prosecuting Police Scotland under health and safety legislation over the handling of the tragedy, in which Lamara Bell, 25, and her boyfriend John Yuill, 28, died.

A call was made to police by a member of the public but not acted upon and the couple from Falkirk lay in the crashed Renault Clio until a second call was made.

Read more: Mother of M9 crash victim Lamara Bell says the last year has been 'torture' for the family

Ms Bell succumbed to her injuries in hospital a week after her partner was killed in the crash near Stirling in July last year.

The health and safety legislation involved covers the police's "duty not to endanger others".

The Health and Safety Executive has been asked by the Crown Office to review information compiled by Scottish prosecutors and the HSE has now completed that review and said it "will assist further if required".

A Fatal Accident Inquiry is also expected.

The legal source said the Crown Office is at the stage of "considering a prosecution involving Police Scotland under health and safety legislation".

He added: "The public have concerns with health and safety and we keep getting problems with calls not being responded to, like the case involving Lamara Bell and John Yuill."

The M9 tragedy brought to the fore wider call centre concerns following the creation of the national force in 2013 with the merging of the previous eight forces under a £1bn programme of cuts, bringing the loss of 1,500 jobs.

A review of police call-handling was carried out by HM Inspectorate of Constabulary in Scotland (HMICS) following the deaths of Ms Bell and Mr Yuill.

Read more: Mother of M9 crash victim Lamara Bell says the last year has been 'torture' for the family

After its investigation HM Inspector of Constabulary Derek Penman said staffing levels at the Bilston Glen contact, command and control centre - where the initial call regarding the fatal M9 crash was received - were insufficient and had resulted in "low levels of performance".

A Crown Office spokesman said: "There remains a considerable amount of work to be done on this investigation and it must be conducted with the utmost thoroughness to order to get the families the answers they deserve.

"We will ensure that the relatives are kept fully informed of developments in the case during the ongoing investigation.”

Police Scotland Assistant Chief Constable Wayne Mawson said: "A report by the Police Investigations and Review Commissioner (Pirc) into the circumstances surrounding the deaths of John Yuill and Lamara Bell in July 2015 has been presented to the Crown Office and Procurator Fiscal Service (COPFS).

"Police Scotland has been committed to working with the PIRC and the Crown Office throughout the investigative process.

"Our condolences remain with Mr Yuill and Ms Bell's families and friends and we continue to offer support to all those affected by this tragic incident.

"We continue to implement the recommendations made by HMICS concerning our contact, command and control centres.

"As we have previously stated, we cannot comment on any details whilst the Crown evaluates the independent findings submitted by Pirc."

Read more: Mother of M9 crash victim Lamara Bell says the last year has been 'torture' for the family

Gordon Crossan, president of the Association of Scottish Police Superintendents, said he is unable to comment on individual cases but added there was a changing positive culture in the force in moving to improve the service.

An HSE spokeswoman said: "HSE were asked to review information by COPFS, which we have done, and we will assist them further if required."

The Health and Safety At Work Act 1974 section seven states: "It shall be the duty of every employee while at work to take reasonable care for the health and safety of himself and of other persons who may be affected by his acts or omissions at work."

In 2007 the Metropolitan Police force was found guilty of endangering the public over the fatal shooting of a man officers mistook for a suicide bomber.

The force broke health and safety laws when officers pursued Brazilian Jean Charles de Menezes to a Tube station and shot him seven times, a jury found.

It was fined £175,000 with £385,000 costs over the 2005 shooting.