A confidential report from the company leading the enormous project, WSP/CBP, showed that the project which started out as a prestige endeavour, yet rapidly turned into a farce, could only be finished with a cash injection of €1.1 billion.
Bild newspaper said it had seen the report listing key areas in need of a financial boost as being the building and planning section of the project, as well as sound insulation. Construction costs of the still-unfinished international hub have been climbing steadily since it began in 2006.
Where the additional money would come from was unclear, said airport bosses. It was likely, Bild said, that it would come from public funding.
Managers received an extra €1.2 billion just a year ago, to continue construction. This pushed the cost up to €4.6 billion. The new demand for €1.1 billion would shove this total to €5.7 billion.
It is thought that the airport should finally open towards the end of 2014, or beginning of 2015, years behind schedule.