The army launched a sweeping campaign after Egyptian President Abdel Fattah al-Sisi, who is standing in elections for his second term this month, gave them a three-month deadline to crush IS in Sinai.
He issued his ultimatum in November after suspected IS gunmen massacred more than 300 worshippers in a Sinai mosque associated with Sufi Muslim mystics.
Since the military, then led by Sisi, ousted Islamist president Mohamed Morsi in 2013, security forces have sought to quell attacks by the Egypt branch of IS.
The jihadists have killed hundreds of soldiers, policemen and civilians, mainly in North Sinai but also elsewhere in Egypt.
They have also killed scores of Christians in church bombings and shootings, as well as bombing a Russian airliner carrying tourists from an Egyptian resort in 2015, killing all 224 people on board.
The military says it has evidence IS has sought to move members to Sinai following its defeats in Iraq and Syria.
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