The 1968 Mexico City Olympics are best known for the Black Power protests of the US runners Tommie Smith and John Carlos.

The year 1968 was a highly politicised one.

China was in the throes of the Cultural Revolution, Czechoslovakia's burst of freedom was crushed by Soviet troops, the government of France was almost overthrown by student-led demonstrations, and civil rights and anti-war demonstrations were spreading across the United States.

Mexico was by no means immune to such revolutionary activity.

As the Olympics approached, 300,000 Mexican students and teachers were on strike.

Ten days before the Olympics were scheduled to begin, government troops opened fire on several thousand unarmed students holding a rally in the Plaza de Las Tres Culturas. Hundreds of young people were killed.

The IOC refused to take a stand on this, declaring that the incident was ``an internal affair which was under control''.

Yet exactly two weeks later, when two black men made a silent, non-violent protest, the IOC. was up in arms, condemning Smith and Carlos for their disrespectful behaviour.

Two other controversies of 1968 were the introduction of sex tests for women athletes (first used at the Winter Games in Grenoble) and the altitude of Mexico City (7347 feet).

The rarefied air led to numerous world records in races of short distances, but was disastrous to competitors engaged in endurance events, except those who had trained at high altitudes.