Officials with Cardiff City Council are understood to have queried the ability of the stadium stands to withstand the loading of large numbers of people jumping up and down at the same time.
The stadium is due to hold a sell-out rock concert on new year鈥檚 eve starring the Manic Street Preachers.
Sources at Cardiff City Council, which had earlier given permission for the concert, said talks had taken place with the stadium owners about blocking off some of the stands to ensure crowd safety.
A spokesperson for Cardiff City Council confirmed that officials in its building control department had held talks with the Millennium Stadium about the stands鈥� safety.
She said: 鈥淪afety issues are still being discussed with the Millennium Stadium Plc. We are not prepared to comment further.鈥�
The 拢126 m stadium was completed by Laing just weeks before its official opening for the Rugby World Cup in October.
Fears about stadia with cantilevered stands for non-sporting events were raised in government guidance on sports stadia published in 1997. The guidance, which was based on technical advice offered by the Football Licensing Authority, drew attention to the dangers caused by crowds that jumped up and down for a long time.
An industry source said: 鈥淭he Millennium Stadium has been designed for sport and is perfectly safe for that purpose. But there is a world of difference in static loading for people watch sporting events and the dynamic loading caused by people dancing at concerts.
鈥淵ou need a higher degree of stability in a structure that is being used for rock concerts. If people start jumping up and down at the same time, it can cause movement in a cantilevered stand. That can easily cause panic in people.鈥�
A spokesperson for the Millennium Stadium said it was unaware of a problem and declined to comment.
A spokesman for Laing said: 鈥淲e built the stadium as a multipurpose stadium that could be used for non-sporting events. We are not aware of any problems regarding the stand.鈥�
- An independent report on the 拢475m National Stadium at Wembley has cast further doubt on its viability. There are concerns that it may not convert from football to athletics mode. In a parliamentary answer on Wednesday, culture secretary Chris Smith said he had given the developer two weeks to resolve the problems, hinting that part of the 拢120m lottery grant might be diverted elsewhere.
