Gunmen armed with rocket-propelled grenades attacked several military checkpoints in Egypt’s Sinai region, killing 15 soldiers and two civilians, security sources said.
The attacks defied one of the toughest security crackdowns in the country’s history.
There was no immediate claim of responsibility for the attacks but militants who support Islamic State have previously carried out similar operations in the Sinai Peninsula.
Egypt has endured years of political turmoil following the ouster of president Hosni Mubarak in 2011 , and the biggest Arab state still faces security challenges on several fronts.
Sinai-based militants have killed hundreds of soldiers and police since the army toppled president Mohamed Morsi of the Muslim Brotherhood in 2013 after mass protests against his rule.
Sinai Province
In January, Islamic State's Egypt wing, Sinai Province, claimed responsibility for a series of attacks that killed at least 30 people.
President Abdel Fattah al-Sisi mounted a violent crackdown on the Islamist movement after deposing Mr Morsi. Security forces killed hundreds in the streets and arrested thousands in an effort to neutralise what was once Egypt’s most organised political group.
Sinai Province and other militant organisations opposed to the US-backed government have proven resilient.
Reuters