The source told Bild that construction company Hochtief is in negotiations with the city senate over the project and has asked for additional money.
Intended to give Hamburg a world-famous landmark like Sydney's Opera House – the concert hall already has a €340 million price tag, though initial plans called for only €187 million.
“We are still in negotiations,” Elbe Philharmonic spokesperson Dieter Peters told The Local. “We are not commenting on the matter until they are finished.”
A increase in expenditures has already hit the project. Costs went up by €20 million in March when the philharmonic apparently ran into trouble trying to cool the glass structure to be perched atop a massive brick shipping warehouse right on the Elbe River.
Bild also reported that Hochtief is 23 months behind schedule, but plans to increase machinery and personnel to meet it's 2011 inauguration date.
Peters refused to comment on the reported delays, adding that the philharmonic didn't need to comfort anyone regarding the project.
“The investors are just as informed as we are and there is no need for reassurances,” he said.