Fred Smith, founder of the US parcel delivery giant Federal Express, has died at the age of 80, the company has announced.

Mr Smith founded the firm in 1973, having previously served in the US Marine Corps. He ran the company as CEO until 2022.

"Fred was more than just the pioneer of an industry and the founder of our great company. He was the heart and soul of FedEx," current boss Raj Subramaniam wrote in a memo to staff.

Born in 1944, Mr Smith started FedEx with 389 staff and 14 small planes that carried 186 packages from Memphis to 25 cities within the US.

FedEx now has more than 500,000 employees across the globe and delivers millions of packages a day.

Its operations involve 705 aircraft and 200,000 vehicles, according to its website.

"He was a mentor to many and a source of inspiration to all. He was also a proud father, grandfather, husband, Marine, and friend," Mr Subramaniam said.

Mr Smith joined the US Marine Corps as a second lieutenant after graduating from Yale University.

He served two tours in Vietnam and was awarded medals for bravery and wounds received in combat before leaving the military as a captain in 1969.

Mr Smith used a business theory he developed while at Yale to create what is now known as a hub-and-spoke delivery system.

Such a network relies on coordinated cargo flights centred around a main hub, which Mr Smith set up in Memphis, Tennessee, which remains FedEx's base.

While well-known in Memphis, Mr Smith lived a life relatively out of the spotlight, although he did make a cameo appearance in the Tom Hanks movie Castaway, in which a FedEx employee is stranded on an island after a plane crash.