Egypt's president has vowed that those responsible for stripping an elderly Christian woman and parading her naked on the streets will be brought to justice.

The May 20 attack in the village of Karma in Minya province, south of Cairo, followed a rumor that the woman's son had an affair with a Muslim woman. The armed Muslim mob that assaulted the 70-year-old woman also looted and torched seven Christian houses.

President Abdel-Fattah el-Sissi said on Monday that such attacks divide Egyptians. He says in comments carried live on local TV that "we are all one and the law must take its course."

Egypt's Coptic Christians, who account for about 10 percent of the country's 90 million people, have long complained of discrimination by the overwhelming Muslim majority.