ISIS carried out an attack on Egyptian security forces in Sinai a week ago and captured a Christian criminal research expert, the militant group said
The man was involved in the government's campaign against militants, the group said in its weekly newspaper Al Naba, published on Thursday. It gave no further details.
The attack took place on January 18, west of Al Arish, the capital of the North Sinai province, the group said. One Egyptian officer was killed and two soldiers injured, it said, adding several Egyptian soldiers had been killed or wounded in the past week.
Two security sources in northern Sinai confirmed the incident, saying three security personnel were killed. The Christian man was riding a bus when he was captured, they said.
On Tuesday, the military said Egyptian security forces had killed 59 militants in the Sinai peninsula recently and had lost seven of their own men.
The figures covered the "last period", the military said without specifying dates or locations of operations. It did not give the identity of suspects or their affiliation.
Egypt's military says several hundred militants have been killed since it launched a major campaign in February last year to defeat militants linked to ISIS in Sinai.
The news comes as Egypt marks the eighth anniversary of the uprising that toppled former President Hosni Mubarak. Protests began on January 25 2011 and in the 18 days that followed, an estimated 800 people were killed and thousands more wounded before Mr Mubarak stepped down on 11 February 2011.
Since then the country has undergone a swing back towards authoritarianism, after the first democratically elected president in the country's history Mohammed Morsi was ousted by the military in a popularly backed coup in 2013.
Former army chief and current President Abdel Fattah El-Sisi has overseen the largest crackdown on dissent in the Arab nation's modern history, jailing thousands of Islamists along with secular pro-democracy activists. Rights watchdog Amnesty International said on Thursday that Egyptian authorities have detained at least 113 people in 2018 for peacefully expressing their views, saying the country has become more dangerous than at any time in recent history for anyone openly criticising the government.
On the anniversary of the beginning of the uprising on Saturday there was a heavy security presence but few members of the public in Tahrir Square in downtown Cairo – once ground zero for the protest movement and frequently filled with hundreds of thousands of demonstrators.