Two British-Egyptians and one Egyptian were arrested in a Cairo Metro station for speaking about politics in English.
The three were arrested after a man told authorities he heard them speaking about the January 25 revolution in English.
According to local media, the man accused them of talking about how to destabilise the country during the upcoming anniversary of the revolution.
The Associated Press said a British diplomat had confirmed the detentions.
The three detainees, all in their early 20s, rejected the claims but their case was nevertheless referred to the prosecution.
The latest detentions come as there is a climate of paranoia and suspicion among Egyptians. Earlier this year Le Monde Diplomatique’s Editor-in-Chief Alain Gresh was arrested at a trendy cafe in downtown Cairo after a woman reported him to police for discussing politics.
Gresh and two Egyptians were arrested after the woman screamed at them for speaking about Egypt in English and Arabic.
The French journalist, who was born in Cairo, said he received a formal apology from authorities, including both police and military figures.
The incidents have raised fear among Egypt’s expatriate community and foreign journalists.