The deaths raise military casualties to at least 16 dead, along with more than 100 jihadists, since the start of the operation on February 9, according to previous army tolls.

The army launched the 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.

Sisi issued his ultimatum in November after suspected Islamic State gunmen massacred more than 300 worshippers in a Sinai mosque associated with Muslim Sufi mystics.

IS in Sinai has been among the group's most resilient affiliates, killing hundreds of soldiers, policemen and civilians in Sinai and elsewhere in Egypt.

It has killed scores of Christians in church bombings and shootings, and bombed 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.