Unison said it was announced at a Scottish Police Authority meeting that an 18-month freeze on senior promotions was being ended to improve morale, allowing more than 100 officers to apply for superintendent posts carrying pay rises of up to £8000.
In the last two months, 140 civilian jobs have gone at Police Scotland. The union's regional organiser, Gerry Crawley, said: "It baffles me how, on the one hand, hundreds of staff jobs are being cut but, on the other hand, promotions to the rank of superintendent are being allowed. It would have been a positive sign to support staff by Police Scotland and the Scottish Police Authority if these promotions had been kept on hold and the savings used to keep police staff doing their jobs."
A Police Scotland statement said the force was commited to no compulsory redundancies, adding: "During the transition to a single policing service we have taken a number of steps to improve our efficiencies, which includes reducing the costs of overall management and reducing the numbers of superintending ranks by a third.
"However, while this work has been under way there has been an 18-month hold on any promotions. We are now in a position to fill a number of key vacancies in order to effectively support the service and lead policing teams in keeping people safe."
It came as Scotland's top police officer denied Edinburgh's saunas had been targeted by the country's new single force.
Chief Constable Sir Stephen House told MSPs he had no issue with the way Edinburgh City Council dealt with the venues.