Olympic boss Thomas Bach on Saturday said future Games hosts will have to prove their "sustainability" and that there would be a shake-up of the bidding criteria.

The International Olympic Committee president made the comments to Olympic Council of Asia delegates in Incheon, which has gone into debt to host the current Asian Games.

The German official said the IOC has to "act now" to preserve its "relevance", suggesting cities that pitch for international sports events need to think about the long-term impact.