Wowereit, 59, a senior member of Germany's main opposition Social Democrats (SPD), has faced criticism for the repeated delays in opening the 4.3-billion euro ($5.6 billion) Willy Brandt International Airport.

The delays have tarnished Germany's reputation for efficiency. The delays, caused by red tape and, latterly, problems with the fire-safety system, have turned the airport and its city into the butt of nationwide jokes.

Center>Copyright Reuters, 2013