FILE PHOTO: A Saudi woman celebrates with her friends as she drives her car in Al Khobar, Saudi Arabia, June 24, 2018. REUTERS/Hamad I Mohammed

RIYADH (Reuters) - Human Rights Watch (HRW) launched a campaign on Tuesday urging major car companies to call on Saudi Arabia to release women activists who fought for the right of women to drive in the conservative kingdom.

A ban on women driving was lifted in June as part of Crown Prince Mohammed bin Salman’s bid to transform the economy of the world’s top oil exporter and open up its cloistered society. Many automobile manufacturers celebrated the decision with advertising campaigns.

But the lifting of the ban was accompanied by fresh arrests of some of the very female activists who campaigned against it for years, including Loujain al-Hathloul, Aziza al-Yousef, Eman al-Nafjan, Nouf Abdelaziz, Mayaa al-Zahrani, Hatoon al-Fassi, Samar Badawi, Nassema al-Sadah and Amal al-Harbi.

Saudi authorities have accused them of suspicious contacts with “foreign entities”, and local media labeled them traitors. At least nine people remain in detention, according to New York-based Human Rights Watch.

HRW said it had launched the #StandwithSaudiFeminists campaign after contacting Nissan, Jaguar Land Rover, Hyundai, Ford, Volkswagen VOWG_p.DE, Audi, General Motors and Renault to urge them to act on behalf of the jailed women.

“The companies should speak out for these women who are unjustly behind bars awaiting trial and whose years of activism have created a lucrative new market for the car companies,” said Sarah Leah Whitson, Middle East director at HRW.

Some 3 million women drivers are expected to be on Saudi roads by 2020.

(The story was refiled to fix company coding in paragraph 5)