Image copyright PA Image caption Africa will be Jolie's fifth project as a director

Angelina Jolie has signed up to direct Africa, a film about celebrated conservationist Richard Leakey's battles with ivory poachers.

The screenplay has been written by Eric Roth - who won an Oscar for Forrest Gump.

Leakey is former head of the Kenya Wildlife Service and was key to stemming the trade in illegal ivory.

"I've felt a deep connection to Africa and its culture for much of my life," said Jolie.

Leakey's extreme measures to tackle poachers, including sending helicopter gunships into the national park, have helped Kenya's elephant and rhino populations recover from the brink of disaster.

He made international headlines in 1989, when a stockpile of 12 tonnes of ivory was burned in Nairobi National Park.

Jolie said Africa is about "a man drawn into the violent conflict with elephant poachers, who emerged with a deeper understanding of man's footprint and a profound sense of responsibility for the world around him".

Producer David Ellison - whose company Skydance co-produced films including True Grit and Jack Reacher - called Leakey "inspirational," adding, "Africa is a story that deserves to be told".

Jolie's next movie, Unbroken, starring British actor Jack O'Connell is due in cinemas later this year.

She is currently directing and starring opposite her husband Brad Pitt in the film By The Sea, based on her own screenplay.