American actor Leonardo DiCaprio, 39, has been named a "messenger of peace" by the United Nations (UN) with the aim of raising global awareness of climate change.

The decision was announced on Tuesday by UN Secretary-General Ban Ki-moon. DiCaprio's first official engagement as messenger is scheduled for 23 September, when he will speak at the Climate Summit 2014 in New York, a meeting where dozens of heads of state and government will gather to pave the way for the adoption of a global climate agreement.

"Leonardo DiCaprio is not only one of the finest actors of our time. He is also a long-standing environmental activist through the work of his foundation," said Ban Ki-moon. The Leonardo DiCaprio Foundation was established in 1998 with the aim of protecting endangered species and building a sustainable relationship between humanity and nature. Among its most important causes are the protection of tigers in Nepal, elephants and marine biodiversity.

DiCaprio officially joins that group of "committed" actors which has included and continues to include celebrities such as Audrey Hepburn and Angelina Jolie, George Clooney and Michael Douglas.