As many as 31 Egyptian soldiers were killed in militant attacks in Sinai and the government imposed emergency rule in parts of the peninsula, where the army is battling an Islamist insurgency

At least 26 soldiers were killed when a car bomb exploded at the Karm al-Qawadis checkpoint in northern Sinai yesterday, Dr. Sami Anwar, head of the al-Arish hospital, said by phone. State-run Ahram Gate website put the death toll from the blast at 28, calling it the deadliest attack in more than two years of unrest. Hours later, militants attacked another checkpoint in al-Arish, killing three soldiers, according to Ahram.

Egyptian authorities declared a state of emergency in the part of northern Sinai where the attacks took place, according to a statement from the presidential office. Overnight curfews from 5 p.m. to 7 a.m. will be imposed under the emergency rule, which will last for three months. Army commanders headed by President Abdel-Fattah El-Sisi will hold an emergency meeting today.

Egyptian security forces are battling an Islamist insurgency in the desert peninsula that has escalated since the army toppled a Muslim Brotherhood government in July last year. Yesterday’s clashes took this week’s death toll to more than 40, according to Ahram.

The car at the checkpoint was driven by a suicide bomber, and the high death toll there was due to the storage of ammunition at the site, Ahram said.

The Al-Qaeda-inspired Ansar Bayt al-Maqdis has claimed responsibility for previous attacks in the region, including two bombings in September that killed 17 policemen.

Libya Weapons

El-Sisi, a former army chief who led last year’s takeover, has blamed the Brotherhood for much of the violence against security forces. The group denies the charge, saying it is focused on peaceful protests against its ouster from government after winning a series of elections.

Egyptian authorities have also expressed concern that militants are finding it easy to obtain weapons in neighboring Libya, which has slid into chaos amid feuds between rival armed groups since the overthrow of Muammar Qaddafi in 2012.

The Sinai militants are receiving training from Islamic State, which may extend that support to other groups in Egypt, according to Anthony Skinner, head of analysis at U.K.-based risk forecasting company Maplecroft.

That, coupled with the availability of arms in Libya, means that “militant Islam is unlikely to be vanquished in the short or medium-term in Egypt,” he said by e-mail.

The U.S. State Department condemned yesterday’s attacks and expressed support for “the Egyptian government’s efforts to counter the threat of terrorism.”

The U.S. usually provides about $1.3 billion a year to Egypt’s army, a longtime ally. It cut some deliveries this year because of the military’s overthrow of an elected leader. Secretary of State John Kerry said in June that full aid would resume soon.