Beijing Olympics organisers denied manipulating pollution statistics yesterday as thick smog worsened in the Chinese capital with just 12 days before the opening ceremony.
The first batch of Australian athletes is to arrive in Beijing tonight to be greeted by a wall of pollution that has built up in recent days.
Australian Olympic team officials who arrived in China several days ago confirmed visibility had worsened around the Games precinct with the Main Press Centre, once visible from the athletes' village, now hidden by smog.
The past three days failed to reach the acceptable levels of air quality predicted with hot, humid and still conditions ensuring the pollution lingers.
Vice-director of Beijing Municipal Environmental Protection Bureau Du Shaozhong said yesterday the unfavourable weather conditions had inhibited the positive effect of traffic restrictions imposed last week and insisted it would improve.
''The weather condition in the past several days is not very favourable for the control of pollutants,'' Mr Du said. ''The control measures are very effective but it takes time to see clearer results out of these control measures.
''I have mentioned that we have some unexpected results. Some people are trying to doubt whether we have real improvement or even doubt our statistics and data.
''I believe the air quality will definitely be improved during the Games.''
The Beijing Government has spent $17billion on environmental improvements and while it has made significant advances on air quality it still remains the biggest challenge ahead of the Games.
Mr Du said there were ''back-up'' plans should the unfavourable weather conditions continue but would not reveal what further restrictions would be imposed.
Internet connection is proving to be a problem at the Beijing Games, despite organisers promising uncensored access.
Slow connection speed and apparent restricted access to news websites have riled many of the media outlets already in Beijing.
Yesterday, some media in the Main Press Centre struggled to view various international news websites, including the BBC's Chinese service and appledaily.com.
Japanese reporters said click-through connections would not work.
Connections drop out frequently and several organisations, including the Australian Olympic Committee, say the speed is up to 10 times slower than in Australia.
One picture takes at least two minutes to send.
There are concerns that once the 22,000 media expected at the Games arrive, connections will become even slower. AAP