The leader of the Sinai branch of the Islamic State of Iraq and the Levant (ISIL) group has been killed in a series of air strikes south of the peninsula's El Arish town, according to Egypt's military.

Abu Duaa al-Ansari was killed with 45 other ISIL fighters in an operation guided by "accurate intelligence", Brigadier-General Mohammed Samir, the military's chief spokesman, said on his Facebook page.

He also said the army destroyed arms and ammunition stores used by the group, but did not say when the operation took place.

There was no immediate confirmation from Sinai Province, ISIL's offshoot in Egypt's Sinai Peninsula.

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Egyptian forces have been battling the group for years but the violence has grown deadlier since the 2013 overthrow by the military of Mohamed Morsi, the elected president.

Aaron Reese, a security analyst who specialises in Egypt's Sinai, told Al Jazeera that while the killing is apparently a big victory for Egyptian security forces, it may not reduce attacks.

"A US government estimate says that ISIS in Sinai only has several hundred fighters, so if the Egyptian security forces have killed 45 of them in one blow, that would be a major defeat [to the armed group]," he said.

"But the Egyptian government has announced major defeats like this before, and they have not affected ISIS's operational capacity. So I'm not sure there would be a decline in attacks by ISIS."

The campaign has killed hundreds of soldiers and police and has also targeted Western interests within the country.

ISIL controls large parts of Iraq and Syria and has a presence in Libya, which borders Egypt.