Carly Morris was taken into custody on Monday and the whereabouts of the daughter, eight-year-old Tala, is unknown, said the Washington-based Freedom Initiative, which describes itself as advocating on behalf of people wrongfully detained in the Middle East and North Africa.

“It is unclear if her daughter was detained with her or turned over to her ex-husband”, it said in a statement.

Saudi authorities did not immediately respond to a request for confirmation of Morris’s detention.

US State Department spokesman Ned Price said at a press conference Tuesday that Washington was “aware of the reports that Ms Morris has been detained”.

“Whenever a person is detained abroad, we seek immediate access to visit the individual, to aid him or her with all appropriate consular assistance,” Price said.

“Our embassy in Riyadh is very engaged on this case; they’re following the situation very closely.”

Morris flew to Saudi Arabia with her daughter in the summer of 2019, hoping to spend a few weeks of quality time with the girl’s father.

But soon after they landed in Riyadh, he seized their travel documents and arranged for the girl to become a Saudi citizen, ensuring he could bar her from leaving.

In September, she received a summons from Saudi prosecutors indicating she was under investigation for “disturbing public order”, a development Morris believed was linked to social media posts about her case.

She was then informed that she had been placed under a travel ban, according to an electronic notice seen by AFP.

“I fear I will be arrested at any moment,” she had told AFP after receiving the notice. “My biggest fear will be who will take care of Tara.”