CAIRO — At least 12 Chinese nationals were deported and put on a flight to China late Thursday, and 22 more were detained for immediate deportation, three Egyptian aviation officials said.

According to a Chinese student who said he was friends with some of those detained, all were Uighurs, members of an ethnic group that is mostly Sunni Muslim and lives mainly in the western Chinese region of Xinjiang. The student, Muhammed Emin Nurmuhammed, said that his friends had been studying at Al Azhar, a mosque and university in Cairo.

Two of the aviation officials said that the Egyptian police had ordered them to deport at least 22 Chinese nationals on Thursday without providing an explanation. They were held at a police facility and were to be put on a flight that was scheduled to leave just before midnight.

At least 12 others were forced to leave on an EgyptAir flight to Guangzhou, a third aviation official said. All three aviation officials asked for anonymity to discuss the episodes.