Six of the United States women’s national team refused to sing their national anthem once again at the World Cup, ahead of kick-off in Sunday’s last-16 meeting with Sweden.

The US team, the reigning world champions, have triggered a row that has seen some players labelled “disrespectful” by prominent right-wing voices in the US. 

This was the fourth time that the issue has flared up during this tournament, following similar apparent refusals to sing in their group-stage games against Vietnam, the Netherlands and Portugal.

Just under half of the starting XI did sing, but defenders Crystal Dunn, Naomi Girma and Emily Fox, plus midfielder Andi Sullivan and forwards Sophia Smith and Trinity Rodman, all appeared not to be joining in.

The incident suggests a political division within the squad, at a time when a good team performance on the pitch was critical against the Olympic silver-medallists Sweden, off the back of an underwhelming group stage from the USA.

Among the critics of the team has been prominent US media personality, Megyn Kelly, who said the reigning World Cup champions were damaging the country, adding earlier in the tournament on SiriusXM’s the Megyn Kelly Show: “I really do believe their version of what a feminist is, what it means to be an empowered woman, at least as an American woman, means you need to hate your country.

“It means to go out on the national stage and embarrass yourself and your country by not singing the national anthem. For several of them, not even holding their hands over their hearts when the national anthem played, that was a bridge too far.

“They couldn’t be bothered to actually place their hand on their heart as the national anthem played, as they stood out there representing you and me and the country and our military and people who have given their lives for the country that they represent. It was too much of an effort [for them] to place their hand over their heart, or God forbid, sing.”

Others, including star striker Alex Morgan, could be seen singing.

Girma brushed off the criticism earlier in the competition, although has yet to explain why some players appear to be protesting, saying: “I think when we’re out there we’re preparing for the game, and that isn’t the focus,” Girma said. “So ultimately, every player has the choice.”

Protests by players around the anthem date back to 2016, when outspoken player Megan Rapinoe was inspired to take a knee after American football player Colin Kaepernick did the same to highlight racial inequality and police brutality in the US.

Rapinoe said before the last World Cup in France in 2019: “I’ll probably never put my hand over my heart. I’ll probably never sing the national anthem again. I feel like it’s kind of defiance in and of itself to just be who I am and wear the jersey, and represent it.”

The women’s team were in a long-running dispute with US Soccer until February last year, when their equal pay lawsuit against the federation was settled for $24 million (£19 million).