Egyptian security forces killed 52 suspected militants in North Sinai, the military said in a statement on Monday.

Security forces launched a large-scale operation in February to crush militants who have waged an insurgency that has killed hundreds of security forces and residents over many years.

Their deaths bring the total of suspected Islamist militants killed since the beginning of the operation to at least 509, according to Reuters calculations based on military statements.

The statement described those killed as “very dangerous” and said they were in possession of automatic rifles, ammunition, grenades and a drone.

Half of the militants were killed in al-Arish, the capital of North Sinai province, the statement said. Three military personnel were killed, it said.

Militants in Sinai intensified their attacks after the ousting by President Abdel Fattah al-Sisi and the military in 2013 of Egypt’s first freely elected president, Mohamed Mursi of the Muslim Brotherhood.

Defeating the militants and restoring security after years of unrest has been a promise of Sisi, re-elected in March in a landslide victory against no real opposition.

Sisi’s critics accuse him of cracking down on all dissent. Supporters say tough measures are needed to stabilize Egypt, which was rocked by years of unrest after protests toppled veteran leader Hosni Mubarak in 2011.

The media is not given direct access to cover high-security operations in Sinai. (Reuters)