Seattle Seahawks star Michael Bennett on Wednesday accused police in Las Vegas of racism and excessive force after a gunpoint confrontation following the recent Floyd Mayweather-Conor McGregor fight.

In a post on Twitter titled "Equality", Bennett detailed how he was detained by police following the August 26 fight as a crowd scattered after hearing what was feared to be gunshots.

Bennett, who has spoken out in support of former San Francisco 49ers quarterback Colin Kaepernick's anthem protests over police brutality, said he was targeted by law enforcement because of his ethnicity.

"Like many of the people in the area I ran away from the sound, looking for safety," Bennett wrote.

"Las Vegas police officers singled me out and pointed their guns at me for doing nothing more than simply being a black man in the wrong place at the wrong time."

READ MORE: LeBron James - Racism is 'part of America'

Bennett said after obeying an instruction by a police officer to get on the ground, the same officer "placed his gun near my head and warned me that if I moved he would 'blow my f****g head off'".

Police later attributed a report of gunfire at Drai's nightclub at the Cromwell resort to the sharp sound of velvet rope stands being knocked to a tile floor.

Bennett, the 193cm defensive end who has been a leader of the national anthem protests started by Kaepernick, said he was among several hundred people running away.

"All I could think of was 'I'm going to die for no other reason than I am black and my skin colour is somehow a threat,'" he wrote. He said he thought of his wife and children.

Bennett said he was taken to the back of a police car "until they apparently realised I was not a thug, common criminal or ordinary black man but Michael Bennett a famous professional football player." He was released without charges.

Las Vegas police Officer Jacinto Rivera said police were checking for casino and police body camera video and written reports. He said the department couldn't immediately verify Bennett's account or identify the officers involved.

"Without looking at video footage or reading any reports we can't say yet what happened," Rivera said.

Bennett's lawyer, John Burris in Oakland, California, defended his client's actions during the incident.

"We think there was an unlawful detention and the use of excessive force with a gun put to his head," Burris told The Associated Press. "He was just in the crowd. He doesn't drink or do drugs. He wasn't in a fight. He wasn't resisting. He did nothing more or less than anyone in the crowd."

READ MORE: More black American footballers join inequality protest

Advocates on Wednesday cited Bennett's treatment by police as an illustration of troubled race relations in the United States.

Patrisse Cullors, a cofounder of the Black Lives Matter advocacy group, called it "a testament to the police violence targeting black people in the United States".

Jocelyn Benson, chief executive of the non-profit Ross Initiative in Sports for Equality, released a statement crediting Bennett with "courage and leadership in addressing issues of racial injustice in our country".

"The revelation of Michael Bennett's terrifying experience with Las Vegas police officers last month underscores the need to continue fighting against racial profiling and inequality," Benson said.