American double Olympic champion Jim Hines, who became the first man to run the 100 metres in less than 10 seconds in 1968, has died at the age of 76.

Hines was born in Dumas, Arkansas, in September 1946, but was raised in California.

Hines was an all-around athlete, playing baseball in his teens, before focusing on track athletics.

In June 1968, Hines was part of history at the United States AUU Track and Field Championships, where he was one of three athletes to be clocked (on hand-timing) faster than 10 seconds during the various rounds of the 100m competition.

His 9.9 seconds heat time was the first to be hand-clocked at sub-10 seconds, although it was later assessed as 10.03 seconds on electronic timing.

Hines finished second behind Charlie Greene in the final, but qualified for the Olympic Games. 

Four months later Hines would win gold in the 100m at the 1968 Olympic Games in Mexico City, clocking 9.9 seconds hand-timed, but confirmed electronically as 9.95 seconds to set a world record.

Hines's world mark would last until 1983 until compatriot Calvin Smith ran 9.93. The 15-year gap was the longest between new benchmark times in the era of world athletics using only electronic timing.

His performance was one of several world records to fall in Mexico, where the Games were held at an altitude of more than 2,000m.

Hines also won gold in the 4x100m relay at the same Olympics, before retiring from athletics to play in the National Football League (NFL) with the Miami Dolphins and the Kansas City Chiefs.

One of his teammates from the US Olympic team from 1968, sprinter John Carlos — who made headlines with Tommie Smith when he made a "Black Power" salute on the podium after winning bronze in the 200m — paid tribute to Hines.

"A very dear friend as well in the name of Jimmy Hines I understand that God called him home today and we send the prayers up for him," Carlos posted on his Facebook page.

"World Athletics is deeply saddened to hear that legendary US sprinter Jim Hines died on Saturday," the governing body said in a statement.