IS attack in Egypt's Sinai kills 70

Smoke rises in Egypt's North Sinai along the border with southern Israel, July 1, 2015.[Photo/Agencies]

ISMAILIA, Egypt/CAIRO - Islamic State insurgents attacked several military checkpoints in Egypt's North Sinai on Wednesday in a co-ordinated assault in which at least 70 combatants and civilians were killed -- one of the biggest militant attacks in Egypt's modern history.

The action marked a significant escalation in violence in the Sinai Peninsula, located between Israel, the Gaza Strip and the Suez Canal.

It also raised questions about the government's ability to contain an insurgency that has already killed hundreds of police and soldiers.

Islamic State's Egyptian affiliate, Sinai Province, claimed responsibility for the attacks.

The army said five checkpoints were hit by about 70 militants and the fighting raged for more than eight hours.

One security source put the number of militants at about 300, armed with heavy weapons and anti-aircraft weaponry.

Security sources said the militants had planned to lay siege to Sheikh Zuweid town, where most of the fighting has been concentrated, by hitting all army checkpoints simultaneously.

"But we have dealt with them and broke the siege on Sheikh Zuweid," one source said.

Army F-16 jets and Apache helicopters strafed the region. Soldiers had destroyed three landcruisers fitted with anti-aircraft guns, the army said.

The insurgency, which is seeking to topple the Cairo government, has intensified since 2013, when then-army chief Abdel Fattah al-Sisi removed President Mohamed Mursi of the Muslim Brotherhood after mass protests against his rule.

Sisi, who regards the Brotherhood as a threat to national security, has since overseen a harsh crackdown on Islamists.

The courts have sentenced hundreds of alleged Brotherhood supporters to death in recent months. Mursi himself, and other senior Brotherhood figures, also face the death penalty.

Sisi's government does not distinguish between the now-outlawed Brotherhood - which says it is committed to peaceful activism - and other militants.

Wednesday's assault was the second high-profile attack in Egypt this week. On Monday, the prosecutor-general was killed in a car bombing in Cairo.