Paris Saint-Germain midfielder Idrissa Gueye has been asked by the French soccer federation why he sat out a game in which players wore jerseys with rainbow-colored numbers to denounce anti-gay discrimination.

A person with direct knowledge of the incident told The Associated Press on Tuesday that Gueye did not play because he did not want to wear a rainbow-colored number on his shirt. The person spoke on condition of anonymity because Gueye has not commented publicly on the incident.

The federation's ethics council sent Gueye a letter, obtained by the AP on Wednesday, urging him to clarify why he missed Saturday's game.

The council said if the reports are untrue, the Senegal international could take a photo of himself wearing the jersey.

"Your absence has led to many speculations that have been very widely interpreted as a refusal to take part in this operation to raise awareness of the fight against discrimination," council president Patrick Anton wrote.

Gueye traveled with his teammates to Montpellier for the game, but PSG coach Mauricio Pochettino cited "personal reasons" to justify Gueye's absence from the field.

"Either these suppositions are baseless, in which case we ask you to express yourself without delay in order to stop these rumors," Anton wrote. "We invite you, for example, to accompany your message with a photo of you wearing the jersey in question.

"Or these rumors [reports] are true," he continued. "In which case, we ask you to take stock of the impact of your actions and the very serious mistake committed. The fight against discrimination affecting different minorities is a vital and constant fight. Whether it's skin color, or religion, or sexual orientation, or any other differences, all discrimination is based on the same grounds -- the rejection of others."

For the second straight season, French clubs were invited to label their shirts with numbers colored from the rainbow flag, the symbol of the LGBTQIA+ movement.

Gueye had also missed the equivalent match in May last season.

"By refusing to take part in this operation, you are validating discriminatory behavior [and] the rejection of others, and not just against those in the LGBTQ+ movement," Anton continued. "The impact of soccer in society and the way players are role models for those who admire them gives all of us a personal sense of responsibility. We hope this letter makes you conscious of the fact you need to clarity your position, or to make amends."

The case quickly became a political issue in Senegal and in France.

Senegalese President Macky Sall tweeted his support to Gueye.

Abdoul Mbaye, a former Senegalese prime minister, also threw his support behind Gueye, saying the PSG player "is not homophobic. He does not want his image to be used to promote homosexuality. Leave him alone."

Homosexual relationships are considered a crime in Senegal and can be punished with up to five years in prison.

Valerie Pecresse, the conservative candidate in the French presidential election last month, joined the criticism of Gueye.