Egyptian soldiers sit atop a military personnel carrier in Sinai. Dozens of Islamic militants unleashed a wave of simultaneous attacks in the region. Source: AP

Officials said at least 70 had died on the Egyptian side, mostly soldiers, though the military in Cairo admitted only 17 deaths.

Many more gunmen from the Islamic State franchise in the Sinai were reported killed when the Egyptians sent in F-16 warplanes and helicopter gunships to beat back the devastating onslaught.

The multi-pronged assault was sudden and tightly co-ordinated, allowing the insurgents to seize control of parts of the town of Sheikh Zuweid in the northern Sinai, near the border with the Palestinian enclave of Gaza.

The fierce fighting means ­Israel is now bracketed by chaos. To the north, the Syrian civil war has encroached on the Israeli-controlled Golan Heights, where al-Qa’ida fighters are involved in a rebel drive against the forces of dictator Bashar al-Assad.

And now in the south, the long frontier running from Gaza through the rugged Sinai desert is coming under growing threat.

Israeli Prime Minister Benjamin Netanyahu said his country stood as “partners’’ with Egypt and other Arab states against ­Islamist terrorism.

“We send our condolences to the Egyptian government and the people of Egypt, to the fallen Egyptians slain by ISIS terror,’’ he said, using an alternative name for Islamic State.

Agence France-Presse quoted a senior Egyptian officer as saying: “This is war’’.

The insurgency in the Sinai has featured assassinations of government officials and intensifying ­attacks by the local Islamic State charter, but yesterday’s all-out ­offensive invites fearsome retaliation by Egypt’s powerful military.

The sunrise assaults on 15 ­military checkpoints and police stations were made by hundreds of fighters with all the hallmarks of an Islamic State operation.

In some places, suicide bombers went in under a barrage of mortar and rocket fire, backed by snipers. Roads were mined to stop Egyptian reinforcements being rushed to besieged outposts.

In Sheikh Zuweid, a Bedouin town about 20km south of the ­fortified border with Gaza, ­militants struck targets with truck-mounted anti-aircraft artillery. A 19-year-old non-combatant was killed in the divided city of Rafah, on the Egyptian-Gaza border, when a rocket went astray.

Last night, the Egyptian air force was continuing to pound the gunmen, while Egyptian armour clattered into action. Following a meeting of generals, the Egyptian military said: “We won’t stop until we purify the Sinai’’.

President Abdel Fattah el-Sisi suggested a crackdown launched earlier this week in response to the murder of Egypt’s top prosecutor, Hisham Barakat, in a car bombing in Cairo, could extend to the fast-track execution of terrorists convicted of capital offences.

The bloodshed in the Sinai comes on top of last Friday’s rampage by a lone gunman on a resort beach in Tunisia that killed 38 people, the majority of them British holidaymakers, and the deadly bombing of a Shia mosque in ­Kuwait for which Islamic State claimed responsibility.

The Tunisian government said last night it had arrested 12 people in connection with the beach strike, and was hunting two ­terrorists who had allegedly trained in Libya with the perpetrators of March’s Bardo Museum atrocity in the capital Tunis that left 22 dead, including Australian dual national Javier Camelo.

The extremist group has issued a call inciting followers to violence during Islam’s holy month of Ramadan. The push by the Sinai offshoot of Islamic State also coincided with the second anniversary of the overthrow of Egypt’s ­Islamist president, Mohamed Morsi of the Muslim Brotherhood, in a coup led by Mr Sisi.

As fighting raged in northern Sinai, senior Muslim Brotherhood figure Nasser al-Houfi was killed along with eight other members of the banned group during a police raid on a Cairo apartment.

Additional reporting: Agencies