Concerns have been raised that a deal to sell publicly owned land and property in the Old Town was rushed through too quickly.
Councillors sold a series of local authority buildings to a South African consortium, headed by developers Artisan and MAS, for £3.4 million last week.
The Evening News revealed the developer is now considering scaling back its original scheme for the Caltongate site.
Steve Burgess, convener of the Green group on the council, said: “The Caltongate sale is a massive missed opportunity. Despite having two years to consider what to do with the site, we’re now told the only option is to hand over council land and buildings to a new developer but with no guarantees.
“I’m very concerned this is being rushed through with little scrutiny when the Old Town will have to suffer the consequences for decades to come.
“On this, and on the closure of Leith Waterworld, we have seen scant regard for the long-term interests of the city and its citizens.”