Red-faced authorities said Tuesday they had delayed indefinitely the opening of Berlin's new main airport due to fire safety problems, in a shock move that angered politicians and the industry. Berlin-Brandenburg International Airport is designed to replace the region's current two hubs, Schoenefeld and Tegel -- a holdover from Germany's Cold War division -- and was to welcome its first flights on June 3. Acknowledging his "bitter disappointment", airport chief Rainer Schwarz apologised at an impromptu press conference and said he was now aiming for an opening "after the summer break", probably in August, without setting a date. He was joined by Berlin Mayor Klaus Wowereit and Brandenburg state premier Matthias Platzeck, who said he was "furious" about the sudden announcement, which is likely to spark a flurry of lawsuits. "This is not a good day for Berlin-Brandenburg airport, the citizens of our states or the many visitors to our region," Wowereit added. "You can imagine that we did everything possible in the last few months to try to achieve an opening date of June 3." Platzeck assured travellers that there was no reason to think that those who had already booked flights this summer would face cancellations, noting that Schoenefeld and Tegel would continue operations. But Germany's state-owned air traffic service DFS said it only learned of the delay Tuesday and that it would require adjustments throughout the global air traffic network. "We have to inform all affected airlines worldwide that they must change their planning," Ralph Riedle of DFS told the Financial Times Deutschland newspaper. The country's top two airlines, Lufthansa and Air Berlin, expressed "regret" over the delay and said they would have to scramble to adjust their schedules. But they stressed the new airport needed to be ready before it could begin service. "We cannot afford in Berlin the kind of chaos they had at London-Heathrow," a Lufthansa executive who asked to remain anonymous told German news agency DPA, referring to cancellations and baggage system turmoil seen at Terminal 5 after its opening in 2008. The massive construction project, on the site of the current Schoenefeld airport, has been dogged by repeated delays. The news, however, hit like a bombshell less than a month before the official opening. "It is outrageous that this delay has been announced 10 days before the chancellor was to speak at a celebration ahead of the opening," a government official told the daily Bild's online edition. "This is a very, very embarrassing situation," added the president of the chamber of commerce in the Brandenburg state capital Potsdam, Victor Stimming. Authorities said the latest delay was rooted in the fire safety system, which has been installed but will not be able to undergo a full battery of checks in time. The airport said more than 7,000 construction workers had been employed at the site in a bid to meet the deadline. Berlin's airports are not the country's busiest, with Schoenefeld and Tegel combined welcoming around 24 million visitors a year -- less than half the 56 million passengers serviced at Frankfurt airport in western Germany. But the new facility, built for about 2.5 billion euros ($3.3 billion), is intended to accommodate the sharp rise in air traffic to the region seen in the two decades since the fall of the Berlin Wall and German reunification. It is to service around 27 million passengers a year. Berlin daily Der Tagesspiegel said the delay would cost 15 million euros per month. Berliners were already mourning the closure of Tegel, which is relatively close to the city centre and whose small, hexagonal main terminal is a 1960s relic that allows passengers to hop in or out of a taxi just outside their gate. The new ultra-modern facility, complete with the money-spinning shopping mall common in modern airports, is on the capital's southeastern outskirts in the state of Brandenburg, and accessible primarily by rail.