OSAKA — Poor ticket sales and extremely hot and humid weather are threatening to turn the upcoming International Association of Athletics Federations meet in Osaka into a public relations disaster that could affect Mayor Junichi Seki's re-election prospects later this year.

Aside from spectators, the 11th IAAF World Championships are expected to involve 7,300 people, including nearly 2,000 athletes from 203 countries and territories. The Aug. 25-Sept. 2 championships are second only to the Olympics in terms of size. For many international track and field athletes, they are also second only to the Olympics in terms of importance.

But concerns are mounting over poor ticket sales. While just over 70 percent of the tickets for Saturday's opening ceremony and the men's 100-meter dash Sunday have been sold, IAAF officials said that, overall, only 46.8 percent of available tickets have been sold.