The large number of presidents is because of two major events in addition to the assembly session.

A summit on climate change will be held Sep 22 at UN headquarters, during which world leaders will be called on to agree to demands in a draft new Kyoto Protocol before the final meeting in Copenhagen in December.

Many heads of state and government will go to Pittsburgh Sep 24 for a two-day meeting of the Group of 20 (G20), a follow-up to its London meeting in April.