Saudi Arabia has threatened to withdraw from the Olympics unless a female judo athlete was allowed to wear her headscarf in competition, The Telegraph reported on Friday.
The Saudis said the women could compete only if they were allowed to wear appropriate Muslim clothing.
On Thursday night the International Judo Federation president Marius Vizer said Wujdan Shahrkhani could not fight with a headscarf.
He said the decision was a result of safety concerns and also "according to the principles and spirit of judo".
Judo spokesman Nicolas Messner said the hijab could be dangerous because the sport involved strangleholds and chokeholds.
However, judo federations in Asia have allowed Muslim women to wear hijabs.