Two Saudi women detained since early December for challenging the conservative kingdom’s ban on female drivers announced on Thursday that they had been released after 73 days.

Loujain al-Hathloul and Maysaa al-Amoudi, who both have valid driver’s licenses from the United Arab Emirates, posted messages on social networks after news of their release was reported by The Wall Street Journal.

Ms. Hathloul, who had documented her effort to drive into Saudi Arabia from the United Arab Emirates on Facebook and YouTube in late November, confirmed late Thursday to her 232,000 Twitter followers that she was free.