Egyptian police have detained scores of Chinese students from the Uighur ethnic minority on Beijing's request, forcing dozens into hiding or to flee to Turkey, activists have said.
The sweep began on Tuesday when police raided two restaurants frequented by Uighur students in Cairo and detained at least 37 people, Abduweli Ayup, a Uighur activist in Turkey, told Al Jazeera on Friday.
Dozens more have been arrested since, Ayup, said, including 20 from Cairo's Al-Azhar University who were stopped in the city of Alexandria on their way out of the country late on Wednesday.
They were told they would be deported to China, Ayup said.
"Students, especially those who study religion, are being targeted," Ayup said. "The police are searching apartment by apartment ... In Cairo, people are in hiding. They are terrified. They are afraid to go out."
The detentions come amid reports that authorities in the Uighur homeland of Xinjiang in western China are seeking the immediate return of Uighurs studying abroad.
China blames unrest in Xinjiang, which has included bombings and vehicle and knife attacks, on exiled Uighur separatist groups.
A traditionally Muslim group, many Uighurs complain of cultural and religious repression and discrimination by China.
Lucia Parrucci, a spokeswoman for the Unrepresented Nations and Peoples Organization advocacy group, said rights groups have moved some 60 Uighur students out of Egypt to safety in Turkey on Thursday alone.
Many of those remaining in Cairo "told us that they are afraid to sleep at home out of fear of their own arrest," she said in an email to Al Jazeera.
Some 80 Uighur students have been arrested since the sweep began, she said.
The Chinese government has forced thousands of Uighur students abroad to return home since January 2017, she said, adding that some 90 percent of the estimated 7,000 - 8,000 Uighurs living in Egypt had returned to China.
"We have learned that many of the students have been arrested directly at the airport upon their return and sent to re-education camps. None of them have been able to see family members and no information was provided to their families about their whereabouts," she said.
Human Rights Watch urged Egypt on Wednesday not to send Uighur detainees back to China, saying they faced "persecution and torture" there.
Sarah Leah Whitson, HRW's Middle East director, also urged authorities to disclose the whereabouts of Uighur detainees and grant them access to lawyers.
Unverified videos shared on Twitter showed more than 70 Uighurs sitting on a floor in a government building and others being driven in a truck in handcuffs.
Ayup said rights groups lost touch with the detainees on Friday.
Abdullah, an Asian student of Islam at Al-Azhar university, told the Associated Press news agency that Uighurs were being detained in the Hay el Sabia area of Cairo's Nasr City district. He gave only his first name for fear of reprisals.
"They're mostly arresting the young men," Sumaya, a Uighur woman living in Cairo, told The Middle East Eye on Thursday. "But I know of women who have been taken too, though we hide when we hear the government knocking on our door."
A Chinese foreign ministry spokesman appeared to acknowledge on Thursday that Chinese citizens had been detained in Egypt, saying at a regular briefing that consular officials would visit them.
Geng Shuang, a foreign ministry spokesman, said that "as far as I know, China's embassy in Egypt has sent consular officials to conduct consular visits". He gave no further details.
The Egyptian police denied requests for comment.
Source: Al Jazeera and news agencies