Freelance reporter Austin Mackell, American student Derek Ludovici and translator Aliya Alwi were detained in the Nile Delta city of Mahalla on the same day activists held student strikes to mark the first anniversary of president Hosni Mubarak's overthrow.
General Mostafa Baz, police chief of the northern Gharbiya province, told reporters the three were suspected of having coordinated over the Internet to meet in Mahalla, which has a history of labour strikes, to "incite people to protest."
A security official said people in Mahalla had complained to police that all three were paying people to protest. The authorities have in the past blamed foreigners for plotting unrest.
Alwi said on her Twitter account that they were being charged with inciting protests and vandalism.
"Witnesses have been produced to confirm it," she wrote. "Report against us, filed now. Many witnesses saw us 'offering money to youth to vandalise and cause chaos.'"
