CAIRO: Egyptian security forces killed 10 militants in an exchange of fire and arrested 400 suspects, including foreigners, in a continuing crackdown in Sinai, the army said in a statement carried by state TV on Tuesday. Based on army statements, around 38 militants have been killed since the latest offensive to crush insurgents blamed for a string of attacks began. Egypt launched a major security operation on Friday involving the army and police against 'terrorist and criminal elements and organisations' across the country, according to the army spokesman. President Abdel Fattah al-Sisi, who is seeking re-election in March, ordered the armed forces in November to defeat militants within three months after an attack on a mosque killed more than 300 people, the deadliest such violence in the Arab world's most populous country. The insurgency poses the greatest challenge to the government in a country that is both the most populous in the Arab World and a main regional ally of the United States. Sisi was elected for his first term in 2014 after the army ousted Islamist President Mohamed Mursi following mass protests against his rule.