Cambridge-based developer Ashwell Property Group has admitted the cost hike on the scheme, known as cb1, and cited increases in local land prices as the cause.
The spokesman also blamed additional land acquisition for the cost rise but refused to be drawn on how the extra space fits into RSH's scheme.
The news comes weeks after RSH's original Cambridge station scheme was dropped by Ashwell (Rogers' railway scheme binned by developer ) following its rejection by Cambridge planners in April 2006.
RSH has now gone back to the drawing board after withdrawing an appeal against Cambridge City Council's decision.
Ashwell is currently exhibiting what it describes as 'emerging options' for the Cambridge station area.
Responding to public criticism, the developer has pledged to reduce the height of the development and the amount of planned floor space. It has also promised to increase the number of bus stops and provide a new taxi rank, dedicated cycle routes and pedestrian links.
RSH was unavailable for comment, but a revised masterplan is expected to be unveiled later this year.