A leaked document by officers planning the new force reveals plans to cut the police estates budget by 20%.
The report, seen by The Herald, says the £56 million annual budget for buildings maintenance and running costs will be cut by 10% "in the first instance" and by 20% after three years.
It says the cuts will require an investment in IT and funds to buy out existing leases and relocate staff "to reduce the overall estate footprint".
Labour called for reassurances from the single force's new chief constable, Stephen House, about the extent of the cuts.
In a letter to Mr House, the party's justice spokesman Lewis Macdonald wrote: "There are estimated efficiencies of some £10m from the wider police estate. With roughly one in five police stations therefore at risk, what initial work has been undertaken to identify those stations that are likely to be closed?
"What consideration has been taken to the number of custody cells within stations?"
He also raised concerns about the distances and length of time officers might have to spend transporting those arrested to available cells, and about claims the number of control centres is set to be cut from 10 to three.
The letter also asks: "How does the relocation of officers outlined in these savings match the commitment to local policing?"
The new Police Service of Scotland will be introduced in April and is expected to save £1.7 billion over its first 15 years.
The Herald's sister paper, the Sunday Herald, revealed last month £300m of cuts would be made by 2016 – including the immediate axing of 550 civilian jobs – under plans being prepared by officers heading the transition.
Scotland's existing eight forces run 300 stations, a figure already cut by more than 50 in the past five years.
Labour's spokesman added: "Kenny MacAskill's fingerprints are all over this. With these sorts of cuts, he can't claim that this is nothing to do with him.
"He needs to tell us what he has asked Stephen House to prioritise and what he's outlined as acceptable cuts to our policing budget."
He continued: "I am concerned these proposed savings could lead to significant disruption to policing in our communities."
The SNP Government is committed to maintaining police officer numbers at 17,234, 1000 higher than the 2007 total.
Official figures showed recorded crimes and offences rose for the first time in five years in 2011 to 858,219. Ministers focused on figures showing a fall in those incidents classified as crimes, which tend to be more serious.
A Scottish Government spokesman said: "We have protected, and will continue to protect, front-line police numbers and the 1000 extra officers we have delivered which have helped reduce crime to a 37-year low, while the fear of crime has also fallen.
"The location of police stations is rightly an operational decision for the police and not one for ministers."
Mr House said: "We are facing very challenging savings targets and want to do all we can to reduce costs without impacting on staff jobs. We are considering every other option – that includes estate. But it is frankly an over-simplication to say the option equates to one-fifth of all police stations.
"We are merging 10 organisations with their own office buildings and wider police service estate. We will not be closing police stations.
"We will be prioritising operational police buildings and we will be prioritising service to the public."