The cost of upgrading the aging Olympic Stadium of Athens under plans by Santiago Calatrava will only be «moderately higher» than the initial estimate and not double or triple that figure, the prominent Spanish architect contended yesterday. Responding to a report in the Sunday Kathimerini which claimed he was worried by high budget overruns, Calatrava said the paper’s comments were «wrong and exaggerated.» «Neither I nor any member of my company has made any kind of declaration to the press concerning information on the project, which we understand to be strictly private and confidential,» Calatrava said in a letter to Sports Undersecretary Nassos Alevras, who then made it public. Calatrava said the risk of earthquakes and fluctuations in steel prices would cause a slight increase in construction costs. Five mainly Greek consortia are bidding for the project. Renovation of the 21-year old Olympic complex, which Alevras said was initially budgeted at 83 million euros, includes a steel and glass roof to partially cover the main stadium and the cycling track, as well as walkways through trees and running water.