The Egyptian military says it has killed the head of the Sinai branch of so-called Islamic State (IS), along with dozens of its fighters.

It said Abu Duaa al-Ansari was killed in a series of air strikes on fighters of the Sinai Province - or Ansar Beit al-Maqdis - group.

The air strikes targeted jihadist strongholds near the town of El-Arish.

Sinai Province is Egypt's most active insurgent group and has been linked to deadly attacks in Sinai and Cairo.

The Egyptian military said: "The raids left more than 45 terrorists killed, dozens of others injured and several arms caches destroyed."

Brig-Gen Mohammed Samir said in a posting on Facebook that Ansari was killed in an operation guided by "accurate intelligence".

The posting did not say when the operation was carried out.

The air strikes were on southern and south-western areas of El-Arish, the largest town in northern Sinai.

The jihadist group, which has been active in the Sinai peninsula since 2011, has not commented on the army's statement.

Video threat

Islamist militancy has risen in Egypt since the army deposed President Mohammed Morsi of the Muslim Brotherhood in 2013.

A recent survey conducted by London-based Al-Araby al-Jadid news website said the group had carried out more than 31 attacks in various areas across Sinai within just a two-week period in March 2016.

The group is also a prolific producer of propaganda videos.

On Wednesday, a video said to be from the IS Sinai affiliate issued a rare direct threat to Israel, saying it would soon "pay a high price".