Two Bible Society bookshops have been attacked in southern Egypt.
The shops in Assiut and Minia were completely destroyed after being set on fire on Wednesday.
General Director of the Egyptian Bible Society, Ramez Atallah, said the attackers demolished the shops' metal doors and windows before setting the books on fire.
He said other shops and cars in the cities had suffered similar violence.
The attacks happened amid an outbreak of violence across Egypt as security forces moved to disperse the supporters of ousted president Mohammed Morsi.
Mr Atallah said the attacks on the bookshops were an "attack against the state by a violent minority" and an "attempt to destabilise the nation".
No one was injured in the attacks as staff had closed the stores in anticipation of violence.
Mr Atallah said: "One of the reasons why the government has been so reticent in dispersing the sit-ins was precisely because of the Muslim Brotherhood's many threats of retaliation. So most Egyptians expected the violence.
"Nevertheless, it is heartbreaking to watch on TV this bloodshed between fellow-Egyptians unfolding before our eyes."
The Egyptian Bible Society is asking for prayers:
• That the government may manage to disperse the remaining sit-in with as few injuries and loss of life as possible.
• That these sad incidents would not increase the alienation of the Muslim Brotherhood, but that they would somehow be re-integrated into Egyptian society.
• For protection for all Christian properties across the nation.
• For Christians to have a spirit of forgiveness and love towards those who are perceived as being our enemies.