The murders come days after an ISIS video vowed to increase attacks on minority groupsEgyptian security officials say suspected militants have killed two Christians in the restive north of the Sinai Peninsula, days after an ISIS affiliate group vowed to step up a wave of attacks on Christians. The officials said Saad Hana, 65, was shot dead and his son Medhat, 45, was abducted and burned alive before their bodies were dumped on a roadside in el-Arish on Wednesday. The officials spoke on condition of anonymity because they were not authorised to brief reporters. Coptic Christians, who make up 10 per cent of Egypt’s population, have increasingly come under attack since the military overthrow of an elected Islamist president in 2013. An ISIS video released this week cast them as allies of the West in a war against Islam and vowed further attacks.