The European Commission ordered Greece yesterday to pay back more than 12 million euros in European Union aid that the government had obtained to build Athens International Airport. The Commission said that Greece will need to return 12.78 million euros, as it overestimated the cost of building the airport, which began operations in March 2001. The correction results from the declaration of actual expenditure which was based on incorrect assumptions, the Commission said. An audit team from Brussels took a look at the airport’s books in March 2002, as part of a review of 70 projects in the EU, and then again in 2003. The Cohesion Fund, which finances the environmental and transport projects of EU members, handed over a total of 250 million euros for the airport, which was one of the city’s key transport changes ahead of the Olympic Games. The Commission is also asking for the return of funds due to the government’s failure to put up the proper notification signs that the project was partially funded by the EU.