'We have adopted a slew of measures to improve aviation safety and have prepared security contingency plans. I am confident we will be able to meet the demands for the Olympics,' Mr Yang said.

Airport traffic will surge this weekend and increase further between Wednesday and August 11 with the arrival of foreign dignitaries, including more than 80 world leaders as well as athletes and visitors.

More than 180 private or chartered aircraft are expected to arrive on Thursday, the CAAC said.

'The challenge is unprecedented in the history of China's civil aviation,' Mr Yang said.

He said the threat of terrorist attacks - which the central government claims is growing as the Games near - had placed enormous pressure on aviation authorities and hundreds of thousands of employees. The CAAC adopted stricter security checks at airports in 19 big cities and at all airports in the Xinjiang and Tibet autonomous regions on July 20.

Capacity limits were imposed at mainland airports last year to ensure safety. Daily throughput at the capital's airport dropped from more than 1,100 flights a day to 1,000.

The airport will be closed between 8pm and midnight next Friday, the day the Games begin, because of security concerns. This will affect dozens of flights.

'We have stepped up security measures mainly because of the changed situation of the anti-terrorism campaign after the March 14 rioting in Lhasa and the March 19 incident,' Mr Yang said. He appeared to be referring to an alleged attempt by a Uygur woman to hijack a China Southern Airlines flight from Urumqi to Beijing, but that happened on March 7.

He said contingency plans had been made to cope with the surge in traffic, and the airport was capable of handling more than 1,750 flights per day, or around 100 flights per hour, with the co-ordination of aviation authorities across the country and the co-operation of adjacent airports.

Four airports, in Tianjin , Shijiazhuang , Taiyuan and Hohhot , have been chosen to back up the Beijing airport in case of emergency.

According to Mr Yang, the CAAC is also prepared to publish the names of airlines that fail to meet their own service pledges. 'We will severely punish airlines which experience aircraft occupations and other incidents as a result of service reasons which originate with the airline. These measures include cancelling slots at corresponding busy airports.'

Huang Dengke , a senior member of the CAAC's northern regional administration, said Beijing was very likely to be hit by thunderstorms on Friday and Saturday of next week based on data from the past three decades. 'We are fully prepared for bad weather before and during the Games.'