The move came amid worldwide protests over the death of George Floyd, a black man killed after white police officer Derek Chauvin, now charged with second-degree murder, knelt on his neck for more than eight minutes.

Players have been unable to kneel or sit during the national anthem since February 2017, with the rule put in place after Rapinoe took a knee during the anthem at a pair of national team matches in 2016.

She did so to express solidarity with Kaepernick, the former San Francisco 49ers quarterback, who took a knee before National Football League (NFL) games to raise awareness of police brutality and racial injustice.

In a statement, US Soccer admitted it was "wrong" to prevent athletes from protesting in this way. 

"It has become clear that this policy was wrong and detracted from the important message of Black Lives Matter," the statement said.

"We have not done enough to listen - especially to our players - to understand and acknowledge the very real and meaningful experiences of Black and other minority communities in our country. 

"We apologise to our players - especially our Black players - staff, fans, and all who support eradicating racism.

"Sports are a powerful platform for good, and we have not used our platform as effectively as we should have. 

"We can do more on these specific issues and we will."

US Soccer's policy reversal comes after a similar move from the NFL. 

NFL Commissioner Roger Goodell released a video apologising for the league’s previous stance on peaceful on-field protests last week. 

The worldwide demonstrations have sparked yet another debate on athletes' right to protest. 

The International Olympic Committee's Rule 50 states: "No kind of demonstration or political, religious or racial propaganda is permitted in any Olympic sites, venues or other areas."

Under Rule 50 guidelines developed by the Athletes' Commission, announced in January, competitors who demonstrate at the Games had been threatened with disciplinary action.

IOC President Thomas Bach revealed this rule could come under review, however, claiming the IOC Athletes' Commission will "have dialogue with athletes around the world to explore different ways for how Olympic athletes can express their support for the principles enshrined in the Olympic Charter in a dignified way".

Conversely, Commonwealth Games Federation chief executive David Grevemberg has pledged athletes who protest at Birmingham 2022 will not be banned or punished. 

"People say are we opening Pandora’s box but no, we are respecting people’s rights to voice opinions," he said, as reported by The Guardian.

"The Black Lives movement is challenging all institutions to really look introspectively at what we can do to be more fair, more free, have better equality and have better systems of justice that look after people. 

"Sport is no different.

"We are comfortable with the uncomfortable conversation and we need to embrace it. 

"We maybe have more responsibility because of the shared history of the Commonwealth so we need to find solutions that don’t build walls but rather build bridges."