The suspect, identified only as Hana, had called police via the mobile phone to warn against an alleged terror attack on the Pope Shenouda in Sohag.
Policxe traced the mobile phone number and arrested Hana who admitted having made the calls. But he failed to give an explanation.
The hoax came amid rising tensions in the neighbouring city of Minya between authorities and Coptic clerics over building a new church. Christians account for an estimated 10 million of Egypt's mostly 80 million population.