A leak in the 'Bird's Nest' Olympic Stadium during a test event last weekend has landed venue managers of the iconic centrepiece of the Beijing Games in hot water. It is also the first public relations test since the multibillion-yuan stadium opened less than a week ago. Officials insisted the damp conditions, which affected part of the stands and a few backroom offices on Sunday as a marathon finished inside the venue, were accidental rather than structural, and would be fixed in days. They were also quick to switch into damage control mode to head off growing doubts about the overall quality of the 3.5 billion yuan (HK$3.9 billion) arena. 'You might have seen leaks in a few places, but at the bottom of it was a single piece of torn membrane which covered the stands,' a senior stadium manager said. 'The perforation was caused by a fireworks rehearsal for the opening ceremony carried out a few days before the marathon. A mistake was made as our staff failed to replace the damaged membrane in time for the test event.' Li Xinggang, one of the chief designers of the 'Bird's Nest', told the Modern Express newspaper that leaks were normal for a project in progress. Without providing details, he said 'things would be resolved when all of the construction was finished'. Workers will put the finishing touches to the stadium, whose main structure has been completed, on May 20. The membrane roof over the interwoven steel structure is an eye-catching feature of the venue and helped earn the arena its nickname. But it has become a source of embarrassment for Beijing's Olympic organisers, who apparently fear critics might link the leak with substandard quality of construction. Public infrastructure projects on the mainland have long been known for their fragility thanks to widespread corruption by unscrupulous contractors and government officials. Beijing authorities have repeatedly promised that such unscrupulous activities would not be a part of the Games. The venue official said a public statement was being prepared to clarify the details of the incident.