Ther former NFL player, who ignited controversy in 2016 after kneeling during pre-game renditions of the US national anthem to draw attention to racial injustice, said protesters had been left with no choice after the police killing of George Floyd.

Quarterback Colin Kaepernick (center), linebacker Eli Harold (left) and Eric Reid (right) kneel in protest during the national anthem before a NFL game last season. September 25, 2017. (Reuters)
Quarterback Colin Kaepernick (center), linebacker Eli Harold (left) and Eric Reid (right) kneel in protest during the national anthem before a NFL game last season. September 25, 2017. (Reuters) (Reuters)

Former NFL quarterback-turned-civil rights activist Colin Kaepernick on Thursday voiced support for protesters who have demonstrated against the killing of an unarmed black man in Minneapolis.

Kaepernick, who ignited controversy in 2016 after kneeling during pre-game renditions of the US national anthem to draw attention to racial injustice, said protesters had been left with no choice after Monday's killing of George Floyd by police officers.

Floyd, a 46-year-old restaurant worker, died after being pinned to the ground with one police officer pressing a knee into his neck for several minutes. The arrest, which was captured on video, showed the handcuffed Floyd gasping for air and pleading that he can't breathe.

It was the latest in a series of deadly confrontations between police and unarmed black men in recent years that have triggered outrage.

Floyd's killing sparked violent protests in Minneapolis, with demonstrators clashing with law enforcement, looting and setting fire to shops on consecutive nights.

Former San Francisco 49ers star Kaepernick, who was effectively ostracised by the NFL after his protest, defended the right of demonstrators to lash out.

"When civility leads to death, revolting is the only logical reaction," Kaepernick, 32, wrote on Twitter in his first public comments on the case.

"The cries for peace will rain down, and when they do, they will land on deaf ears, because your violence has brought this resistance," added Kaepernick, who has been frozen out of the NFL since being released by the 49ers in early 2017.

"We have the right to fight back! Rest in Power George Floyd."

The four police officers involved in Floyd's arrest in the midwestern US city have been sacked and have faced calls to be charged with murder.

Kaepernick's comments on Thursday followed widespread revulsion throughout the sports world, with several prominent figures including NBA star LeBron James voicing their disgust at Floyd's killing.

Los Angeles Lakers ace James was one of several celebrities who contrasted Kaepernick's peaceful kneeling protest with the circumstances of Floyd's death.

"This... ... Is Why," James posted on his Instagram feed, with side-by-side photos of the white policeman kneeling on Floyd's neck and Kaepernick kneeling on the sideline.

"Do you understand NOW!!??!!??" James wrote. "Or is it still blurred to you?? #StayWoke".

Golden State Warriors head coach Steve Kerr said simply: "This is murder. Disgusting."

Lakers legend Magic Johnson also hit out, saying Floyd had been "clearly murdered."

"How many times do we have to see black men killed on national television? This has been going on for entirely too long," Johnson said.

"We need to start seeing black people as human beings and not animals on the street."

Source: AFP