Police Scotland has been urged to do more to tackle the "frightening" number of rest days owed to officers.
Figures obtained by radio station LBC found that as of March this year 25,036 rest days were owed to serving constables, sergeants, inspectors and chief inspectors.
The Scottish Police Federation (SPF), which represents the rank and file, said the figure was the equivalent to a thousand officers having six weeks off work or 150 years' of rest days, a claim described as "utterly misleading" by the force.
SPF general secretary Calum Steele told the station: "The police service is woefully understaffed. It's over-stretched.
"It's being asked to do far too much with the resources that are available to it and what these figures show is that it is actually frontline working police officers that are carrying the brunt for the shortfalls that they've inherited.
"The fact that the police service has got to a situation where it owes over 25,000 rest days to the police officers in Scotland is simply frightening.
"What's self-evident at this moment in time is that the police service lacks the finance, the money, the people, to do all that's asked of it and the Chief Constable, and indeed others, need to stand up and make that point loudly and clearly.
"They also have to make sure that they put in place structures within the police service to make sure that they're not overworking their staff."
Scottish Liberal Democrat leader Willie Rennie said: "These figures are simply astonishing. The fact that so many rest days have been cancelled reveals a deeper problem that exists within Police Scotland.
"It shows the real pressure that the force is under and how this is impacting on individual officers.
"Police officers have been stretched to breaking point and I think we need to step in to make sure we can relieve that pressure so that they can get their lives back."
Peter Blair, Police Scotland's head of resource management, said: "The amount of days owed works out at well under two days per officer, therefore it is utterly misleading to suggest that Police Scotland owes its officers many years worth of time.
"When an officer is required to work on a rest day it is re-rostered if officers are given more than 15 days' notice.
"If less than 15 days, then officers up to and including the rank of sergeant are entitled to claim overtime in the form of time off in lieu or payment.
"This is in line with police regulations, the re-rostering of rest days is a local operational policing decision."