Six times Formula One motor world champion Lewis Hamilton said he felt "completely overcome with rage" as he urged people to speak out against racism.
Hamilton had slammed his sport on Sunday for its silence over the killing of George Floyd, an unarmed black man who died in Minneapolis after a white police officer knelt on his neck.
The death has triggered a wave of outrage and violent protests in the United States.
"This past week has been so dark, I have failed to keep hold of my emotions," said Formula One's first black champion in his latest social media post to millions of followers.
"I have felt so much anger, sadness and disbelief in what my eyes have seen," added the Mercedes driver.
"I am completely overcome with rage at the sight of such blatant disregard for the lives of our people.
"The injustice that we are seeing our brothers and sisters face all over the world time and time again is disgusting, and MUST stop."
Hamilton, who has homes in the United States, drew support from several other F1 drivers and his team after his comments on Sunday.
Formula One also broke its silence with a statement on Twitter: "We stand with you, and all people in the fight against racism. It is an evil that no sport or society is truly immune from," it said.
"And it is only together we can oppose it and eradicate it. Together we are stronger."
Hamilton, 35, cited Hollywood A-list actor Will Smith as saying racism was not getting worse but was being filmed.
"Those of us who are black, brown or in-between see it every day and should not have to feel as though we were born guilty, don’t belong or fear for our lives based on the colour of our skin," said Hamilton.
"Unfortunately, America is not the only place where racism lives and we continue to fail as humans when we cannot stand up for what is right. Please do not sit in silence, no matter the colour of your skin. Black Lives Matter."