The police watchdog is investigating after a man was found dead in a van days after officers were first alerted about concerns over the vehicle.

David Penman, 46, was found dead in a parked van in Dunipace, near Falkirk, on Thursday December 15.

It has been reported in the Scottish Daily Express that concerns over the length of time the van had been parked in a lay-by were raised with Police Scotland days earlier and the force has referred the case to the Police Investigations and Review Commissioner (Pirc).

A review of police call-handling was carried out in the wake of the deaths of Lamara Bell and John Yuill on the M9 in July 2015.

Ms Bell, 25, lay injured for about 72 hours following the accident near Stirling and later died in hospital.

Her partner Mr Yuill, 28, was killed in the crash, which was reported to police the day it occurred but the call was not followed up.

Liberal Democrat leader Willie Rennie called for a "thorough investigation" into the Dunipace incident.

He said: "My thoughts are with the family and friends of the deceased. It send shivers down the spine to have another fail-to-respond case so close to the scene of the M9 crash last year.

"The circumstances may be different but failing to respond to such an incident requires a thorough investigation.

"We need to know the role of Bilston Glen call centre which was implicated in the M9 incident.

"We also need to know whether an overstretched and under-resourced police frontline was a contributory factor. Pirc need to investigate to establish the facts."

Superintendent Martin Fotheringham said: "Police Scotland has reported the circumstances surrounding the discovery of a 46-year-old man's body within a van, which was parked in the Dunipace area of Denny on Thursday December 15, to the Crown Office and Procurator Fiscal Service (COPFS).

"The matter has now been referred to Pirc.

"We will provide any necessary assistance to the Pirc as they conduct their investigation and we await the outcome of their report.

"Our thoughts are with the gentleman's family at this time."

A Pirc spokeswoman said: "COPFS has instructed Pirc to carry out an independent investigation into the circumstances surrounding the death of a 46-year-old man following the discovery of his body in Dunipace, near Denny, on Thursday December 15.

"A report on the commissioner's findings will be submitted to the COPFS in due course."

In a statement issued through Pirc, Mr Penman's family said: "David was a much-loved father, son and brother, and as a family we are devastated by his loss.

"We are now trying to come to terms with this loss and would ask for our privacy to be respected to allow us to grieve in peace."