BEIJING, August 8, 2008 (AFP) - A thick haze loomed over Beijing on Friday ahead of the opening of the Olympic Games as the organisers warned rain could also put a dampener on the spectacular ceremony.

The haze reduced visibility around the Olympic Village in the north of the city to just several hundreds metres (yards), casting a pall over the iconic 'Bird's Nest' national stadium where the ceremony will be held.

Controversy has swirled around the issue of Beijing's air quality throughout the build-up to the Games, but the International Olympic Committee has insisted pollution poses no threat to athletes.

The weather forecast on the official website of the Beijing Olympic Organising Committee (BOCOG) showed a grey cloud with rain falling from it for Friday.

Organisers have repeatedly said rain is their biggest worry ahead of the opening ceremony, which will feature more than 10,000 performers and a massive fireworks display.

Temperatures were expected to range between 25 and 32 degrees Celsius (77 and 90 degrees Fahrenheit) during the day, BOCOG said.