Houses were set on fire and an elderly woman was stripped of her clothing and paraded naked through the streets of a village in Egypt on Friday.
Inter-religious violence erupted in Minya province after rumours of a love affair between a Christian man and a Muslim woman.
The Coptic pope called for restraint.
Coptic representatives said authorities had assured them they would "chase down the perpetrators and bring them to justice".
The Coptic Orthodox Church is the main Christian Church in Egypt.
The attacks happened in Karam village in the central province of Minya on 20 May.
Details emerged late on Wednesday in a statement from the Church, which said Pope Tawadros II was calling for Copts to show "self-restraint".
The Church said that after the Christian man had fled the village, his mother was beaten, insulted, stripped of her clothes and paraded through the streets by a group of people.
Egyptian media said there were up to 300 people involved.
Muslims torched six or seven Christian homes in the village on the same day.
Later, Christians burned down three Muslim homes. Six people were arrested.
Christian men cannot marry Muslim women in Egypt without converting to Islam first. Sexual relations between people who are not married to each other are taboo among both Muslims and Christians there.
Copts make up about a tenth of the country's population of 90 million people.
Copts claims they face discrimination and play a lesser part in Egyptian public life than their numbers justify.
There have also been violent attacks on Copts and their churches by Islamists.