Human Rights Watch is calling on Egypt to quash prison sentences against four Coptic Christian teenagers convicted of blasphemy.

The call by the New York-based rights group came in a statement Monday, a day after Egypt's Justice Minister was fired for saying he would imprison the Prophet Muhammad if he committed a crime, a comment that has widely been viewed as blasphemous.

The teenagers' conviction was based on a video in which they intended to mock the extremist Islamic State group after its Libya affiliate beheaded Coptic Christians last year.

"These children shouldn't face prison for expressing themselves, even with an immature joke," said Nadim Houry, HRW's deputy Middle East director. "Instead of giving in to retrograde views on blasphemy, Egyptian authorities should protect freedom of expression."