Iran’s men’s national soccer team wore black armbands and held schoolbags as their anthem played ahead of a match in Turkey on Friday, in what a team official said was a protest over the killing of schoolgirls on the first day of the Iran war.

Iran were playing a friendly against Nigeria in the Mediterranean resort town of Belek ahead of the World Cup in the U.S., Mexico and Canada, at which their participation is in doubt due to the conflict.

The men lined up holding pink and purple bags with ribbons on them – a reference to the attack on the Shajareh ​Tayyebeh School that Tehran says killed more than 175 people, including children and teachers, on the first day of joint U.S.-Israeli strikes on the country.

Mehdi Mohammad Nabi, a vice president of the Iranian football federation, told Reuters that the players had decided to stage the protest as a symbolic gesture of solidarity with the victims.

“They were deeply affected by the bombing of the girls’ school and wanted to express their sympathy,” Nabi said, speaking in Farsi through the association’s translator. “This was a collective decision by the team. We are united.”

U.S. military investigators believe it is likely that U.S. forces ⁠were responsible but have not yet reached a final conclusion or completed their investigation.

The U.N. rights chief urged Washington on Friday to conclude its investigation into the strike at a meeting of the U.N. Human Rights Council.

Speaking in front of the stadium, Nabi said the team was aware of the discussions taking place at the rights council and hoped for a “clear and appropriate decision”.

Earlier this month, some of Iran’s women’s soccer team stayed quiet during the national anthem at an Asian Cup match, leading state TV in Tehran to brand them “traitors”.

U.S. President Donald Trump ​said earlier this ​month that while ⁠Iran’s national team were welcome to play in the U.S., it might not be appropriate for their “life and ​safety”.

Iran’s football federation said it was in discussions with soccer’s world ​governing ⁠body FIFA about moving its World Cup matches to Mexico from the U.S.

The Iranian team lost 2-1 to Nigeria on Friday and will play Costa Rica on Tuesday in another friendly in Turkey.

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(Reporting by Ece Toksabay, Umit Bektas and Mert Ozkan; Writing by Daren Butler; Editing by Andrew Cawthorne)