The 1.68-billion-baht hike was in line with standard increases in material prices and wages, said Winthai Suwaree, a spokesperson of the National Council for Peace and Order (NCPO).
"Of the total budget, 2.46 billion was for fiscal 2009-14, which can be used to build 181 buildings," Col Winthai said.
The project, which began in 2009, was allegedly fraught with corruption.
The original 12 contracts, grouped by areas to speed up construction, were later combined into one and awarded to a single contractor who failed to deliver after three extensions.
The 6.67-billion-baht contract stipulated that the government pay 15% of the contract value to the contractor as advance payment.
The contractor demolished many old police station buildings but failed to build new ones by schedule, leaving the police scrambling to find new workplaces.
Police were often left working tents, in rented rooms or sharing space with monks at temples.
The contract was awarded to PCC Development Co Ltd during the Abhisit Vejjajiva government in 2010 by former deputy prime minister Suthep Thaugsuban, who oversaw the police then. It was implemented further under the Yingluck government.
Col Winthai said the corruption case, now being handled by the Department of Special Investigation, would continue.
He added NCPO chief Gen Prayuth Chan-ocha felt the project was urgent because as a security force police should have a proper workplace.
Gen Prayuth also asked about the progress of the case and acting police chief Pol Gen Watcharapol Prasarnratchakij told him it was proceeding as it should.
Gen Watcharapol said the work done on the project had exceeded the value of the advance payment. However, damages would be sought from the contractor.