Saudi campaigners have urged Crown Prince Mohammed bin Salman to loosen the conservative kingdom's strict dress code after women took to social media wearing their abayas inside out in protest.
Women in Saudi Arabia have for decades been required to wear the abaya — a loose, all-covering robe — in public, a dress code strictly enforced by police.
Prince Mohammed said in March that women needed only to dress modestly and were not required to wear abayas. But Saudi women say that in practice nothing has changed, and they are demanding more freedom.
"I've started wearing my compulsory hijab called abaya (this black robe) turned inside out to express my objection on Sharia law violating Saudi women's freedom to clothe," tweeted one, referring to the Islamic law that effectively governs the kingdom.
Amani Al-Ahmadi, a Saudi activist with the Euro-Mediterranean Human Rights Monitor, called the protest a "brilliant move" that could create real change.
"To see another woman in flipped abayas — it builds solidarity between women and shows that they are not alone. It is keeping the conversation going and could lead to change," she told the Thomson Reuters Foundation.
"It is another form of dehumanization for women. It forces women to cover up their bodies in order to fit into society and the role of being inferior to men," she said by phone from Seattle, where she lives.
Last year, police briefly arrested a Saudi woman who appeared on a Snapchat clip strolling through an empty alleyway wearing a short skirt and a top that exposed her midriff.
Prince Mohammad was praised for promoting women's rights in the kingdom after he ruled earlier this year they should be allowed to attend mixed public sporting events and drive cars. But since then, more than a dozen activists, most of them women who had campaigned for greater freedoms, have been detained.
Naureen Shameem, a human rights lawyer who works with the Association for Women's Rights in Development, said she supported the social media campaign.
"It's time for real change rather than insincere rhetoric about reform," she said.
Saudi women have started wearing more colorful abayas in recent years, the light blues and pinks in stark contrast with the traditional black. Open abayas over long skirts or jeans are also becoming more common in some parts of the country.
"Many women and girls in the Arab world are still forced to wear the hijab and the abaya either by their family or by their country — and they should have the right to choose," said Suad Abu-Dayyeh, Middle East expert with global advocacy group Equality Now.