Cairo - An unprecedented wave of Islamic State group attacks on Egyptian soldiers in the Sinai Peninsula on Wednesday killed at least 36 people, mostly troops, with the toll expected to rise, officials said.
The dead included several civilians, according to security and medical officials, who said 38 militants were also killed as they battled soldiers and policemen in the North Sinai town of Sheikh Zuweid.
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The attacks, in which car bombs were used, were the most brazen in their scope since jihadists launched an insurgency in 2013 following the army's overthrow of Islamist president Mohamed Morsi.
"It's war. The battle is ongoing," a senior military official told AFP.
"It's unprecedented, in the number of terrorists involved and the type of weapons they are using."
Militants took over rooftops and fired rocket-propelled grenades at a police station in Sheikh Zuweid after mining its exits to block reinforcements, a police colonel said.
The Islamic State group said its jihadists were surrounding the police station after launching the morning attacks on 15 checkpoints and security installations using suicide car bombers and rockets.
Security and medical officials said ambulances could not get to the scene of the attacks because of heavy fighting in which the military brought in Apache helicopters.
"Ambulances are waiting in front of the hospital. They can't leave. People are bringing in the casualties," a health official told AFP.
A medic said one woman killed in the clashes had been brought to hospital by civilians.
Troops regularly come under attack in the Sinai, where jihadists have killed hundreds of policemen and soldiers since Morsi's overthrow.
In a statement released online, IS said it had carried out a multi-pronged assault that involved three suicide bombers.
"In a blessed raid enabled by God, the lions of the caliphate have simultaneously attacked more than 15 checkpoints belonging to the apostate army," the group said.
The attacks came two days after the country's state prosecutor Hisham Barakat was assassinated in a Cairo car bombing.
He was the most senior government official killed in the jihadist insurgency.
President Abdel Fattah al-Sisi pledged to toughen laws and suggested fast track executions following Barakat's death, and a cabinet meeting on Wednesday was expected to pass the amendments.
The government designated Morsi's Muslim Brotherhood a "terrorist group" in December 2013 as part of a crackdown on the opposition that has left hundreds of his supporters dead and thousands in jail.
Courts have sentenced hundreds to death, including Morsi, who was convicted of involvement in attacks on police stations.
His sentence is being appealed.
Months of bloodshed
The government often blames the Brotherhood for attacks, but the deadliest have been claimed by the IS affiliate in Sinai.
Wednesday's attack was similar to a series of ambushes on April 2 in which dozens of militants attacked checkpoints, killing 15 soldiers.
The militants kidnapped a soldier and later executed him, and made off with weapons.
In January, a combined rocket and car bomb attack on a military base, a nearby police headquarters and a residential complex for troops and police killed at least 24 people, most of them soldiers.
The attacks have come despite stringent security measures imposed by the army in the Sinai, including a night-time curfew and the creation of a buffer zone along the Gaza border to prevent militants infiltrating from the Palestinian territory.
The dominant jihadist group in the Sinai, previously known as Ansar Beit al-Maqdis, or Partisans of Jerusalem in English, pledged allegiance to IS in Iraq and Syria last November.
The group is believed to be led by a shadowy Egyptian cleric, Abu Osama al-Masry, and has recruited at least one former special forces officer who had left the military.
The militants have mostly focused their attacks on soldiers and police, killing hundreds since Morsi's overthrow.
They previously said they avoided targeting civilians but claimed responsibility for a suicide bombing on a tourist coach in February 2014 that killed three South Koreans and their driver.
Police foiled an attempted attack at a pharaonic temple crowded with tourists in Luxor last month.
On Tuesday, gunmen shot dead a policeman outside a small museum south of Cairo, and three suspected militants died in an accidental explosion in the capital, police said.