Unison, which represents the force’s civilian staff, said previous Scottish Government pledges to maintain officer numbers while targeting savings totalling £1.1 billion by 2026 were “unrealistic”.
Earlier this week it emerged Police Scotland faces a projected “overspend” of £21m on its £1.1bn annual revenue budget for 2016-17. The figures came a week after statistics showed officer numbers have fallen to their lowest level since 2010 at 17,242.
In a statement, Unison Police Staff Scotland said: “Unison has consistently maintained that the Scottish Government manifesto pledge of 17,234 police officers combined with target savings of £1.1billion by 2026 are both unrealistic and place inappropriate targets and financial imperatives at the heart of Scottish police reform.”
The union said there are hundreds of civilian staff job vacancies across Police Scotland which are not being filled.
It added: “What we are now witnessing is a critical emergency service struggling to deliver a basic service provision, never mind the improvements promised by reform.
“It makes no financial sense to see the Scottish Police Authority (SPA) and Police Scotland continue with de-civilianisation and the abandonment of a cost-effective and balanced workforce model to maintain unsustainably high levels of police officers, deployed in areas which fail to maximise their operational effectiveness.”
Deputy Chief Constable Iain Livingstone said Police Scotland was continuing to engage with trade unions and staff associations to deal with “financial challenges”.
He said: “We are actively scrutinising all non-staff costs in order to achieve the savings we need. Any decisions around budgets will be based upon our commitment to deliver a local service for our communities.”
A Scottish Government spokeswoman said: “We set out in the 2016-17 budget that we will keep police officer numbers at 1,000 higher than in 2007 while at the same time working with the SPA to consider the implications of changing demands on Scottish policing. The SPA and Police Scotland will determine the best possible use of the budget to meet national and local priorities.”