Former US President Barack Obama has described his country’s failure to deal with racial injustice as “America’s original sin”.

In a video for the New York Times, Obama spoke out about the unprovoked murder of black teenager Trayvon Martin in 2012, and the subsequent acquittal of his killer, remembering it ten years on.

Along with civil rights activist and Baptist minister Rev Al Sharpton and literary critic and historian Henry Louis Gates Jr, Obama described his response to the tragedy at the time, saying how he at first responded as a parent, and then as a black parent.

At the time, Obama said: “If I had a son, he would look like Trayvon.”

Gates Jr went as far as to describe the murder of Martin on February 26, 2012, as what 'directly' caused the contemporary civil rights movement to unfold.

The 17-year-old had been returning from a shop when neighbourhood watch co-ordinator George Zimmerman shot him, after ringing police complaining of a suspicious looking character.

Police had warned Zimmerman, of Sanford, Florida, to stop following the young man, but a jury returned a not guilty verdict, claiming Zimmerman had acted in self-defence.

Sharpton told the New York Times: “How dare they say this wannabe security guard had the right, based on this imagined threat, to kill this guy? … When that verdict came in, that verdict said to me ‘y’all have changed the leaders of the system, but you haven’t changed the system’.”

Obama continued: “What it did was to surface what a lot of African Americans had felt for a long time and that I think was a galvanising force in helping to create a broader based movement now known as Black Lives Matter.”

“Hopefully the legacy of this tragedy is not just outrage but something constructive … what happened was unacceptable and this country can do better and my hope is that … people will say that that was the start of America looking inward and in fits and starts coming to terms with what has always been our original sin.”