The opening of Berlin's new €2.5-billion ($3.18-billion) airport must be further delayed until spring of next year, the capital's mayor said Thursday, in a growing embarrassment for city officials.

The airport's planned June 3 opening was canceled at the last minute last week over unresolved fire safety issues but officials then said it could likely be opened this August. But in an about-face, Mayor Klaus Wowereit said the airport's board has now set March 17, 2013, as the new opening date.

Planners and authorities had hoped the opening of the Willy Brandt Airport — named after the former West Berlin mayor and later chancellor — would mark another chapter in the reunification of the formerly divided city.

The project is meant to replace Berlin's two aging airports, Tegel and Schoenefeld, which belonged to West and East Germany respectively.

Officials said last week that all flights booked for the period after June 3 will take place, but passengers will have to travel to the old airports instead.

The fire safety system and other technical infrastructure at the new airport will now be ready by December, leaving three months for thorough testing before the planned opening, the airport said in a statement. The airport's head of technical planning, Manfred Koertgen, was fired by the board of directors over the delay, it said.

It is a "dramatic and unpleasant situation" that has caused serious damage to the region's image, said Matthias Platzeck, the governor of Brandenburg state where the new airport will be located just southeast of Berlin. The new opening date has been agreed upon with major airlines, he told reporters.

The delay will likely lead to cost overruns and liability claims from airlines, but officials have so far declined to discuss figures. The country's two biggest airlines, Deutsche Lufthansa AG and Air Berlin PLC, have both already added new flights that were meant to be operated from the new airport.

Air Berlin CEO Hartmut Mehdorn sharply criticized the airport board's decision. "This is completely unacceptable and inflicts lasting and unbearable damage to Berlin's image as an aviation hub," he said according to German news agency dapd.

"The opening's delay by several months cannot be explained simply by mere fire safety issues," he added. He said the delay also represents a large, but unspecified, financial burden for the company.

The opening had first been delayed from late 2011 to June 2012.

Once it opens, however, the new airport will be able to handle 27 million passengers annually, making it Germany's third-largest hub after Frankfurt and Munich.