U.S. President Donald Trump and U.N. Secretary-General Antonio Guterres are scheduled to speak at a meeting on reforming the world body sponsored by the United States on Sept. 18, the eve of the annual gathering of world leaders at the General Assembly.

Britain also is a co-sponsor and its U.N. ambassador, Matthew Rycroft, said Thursday the event aims "to provide maximum support" for the secretary-general "as he reforms the United Nations at a time when the world requires an effective multilateral system with a well-functioning U.N. at its heart."

U.N. spokesman Stephane Dujarric said Wednesday it's very important for Guterres "to participate and hear from all the member states who are interested in reform."

Trump wants major cuts to the U.N. budget and significant changes to the world organization.