Female chess players have accused the World Chess Federation (FIDE) of failing to stand up for women's rights after it said competitors must accept local law and wear hijabs during the world championship in Tehran, Iran.
Female Grandmasters will risk arrest if they do not cover up during the knock-out tournament next year.
US women's champion Nazi Paikidze has said she will consider boycotting the championships if the decision is not reversed.
"I think it's unacceptable to host a WOMEN'S World Championship in a place where women do not have basic fundamental rights and are treated as second-class citizens," she wrote in her Instagram post.
"For those saying that I don't know anything about Iran: I have received the most support and gratitude from the people of Iran, who are facing this situation every day."
Headscarves have been compulsory for women in Iran since the Islamic Revolution of 1979.
The law is enforced by the country's 'morality police' and any woman found not wearing a hijab in public can be arrested, fined or reprimanded.
Former Pan American champion Carla Heredia says she is unhappy to be discriminated against.
"No institution, no government, nor a Women's World Chess Championship should force women to wear or to take out a hijab," she told the Telegraph.
"This violates all what sports means. Sport should be free of discrimination by sex, religion and sexual orientation."
However, Susan Polgar, chairman of FIDE's Commission for Women's Chess, told the players they must respect “cultural differences.”
"When I visited different places with different cultures, I like to show my respect by dressing up in their traditional style of clothing – no-one asked me to do it, I just do it out of respect," she said in a statement.
"I personally would have no issues with wearing a head scarf (hijab) as long as it is the same to all players.
"I cannot speak on behalf of others, but from my personal conversations with various players in the past year they had no real issues with it."