Unidentified assailants have torched a church used by Egyptian Christians in Libya's eastern city of Benghazi, Flames were seen rising from the church, witnesses said.
The Egyptian Foreign Ministry issued a statement condemning what it described as "assault".
Abdel-Salam al-Barghathi, a security official in Benghazi, said his forces stopped angry men from doing more damage to the church.
He said they were angry about a protest in Cairo by Christians over the death of one of the detainees, whose family says he died of torture.
But Mr al-Barghathi appeared to blame the Christian protesters for the violence. He said the detained Christian died of natural causes and confessed before his death.