Shadi al-Menei, the head of the Egyptian armed group Ansar Bait al-Maqdis, has been killed along with other members overnight, Egyptian security sources say.
The sources said Menei was killed on Thursday while walking in Maghara in Sinai Peninsula, the Reuters news agency reported.
He was the head of Ansar Bait al-Maqdis, or Champions of Jerusalem, which has been behind several recent attacks on Egyptian security forces.
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A statement, posted on the army spokesman's official Facebook page, said the army executed an operation that resulted in the killing of six extremely dangerous criminal elements on Thursday.
It did not name Menei and it was not clear if the statement referred to the same incident.
Several high-ranking security officials confirmed Menei's death, but it was not possible to obtain confirmation from independent sources, the AFP news agency said.
In a separate incident on Thursday, one security officer was shot dead by unknown attackers at a checkpoint in the north Sinai town of Rafah, near the border with Israel, the state news agency MENA reported early on Friday.
Fighters in Sinai increased their attacks against army and police forces last year after the army removed Mohamed Morsi as president. The army then launched a major operation to combat fighters in the peninsula.
Earlier this month, Egypt's prosecutor general charged 200 people with terrorism, accusing them of launching deadly attacks across the country, in the first mass trial of armed fighters since Morsi's overthrow.
The prosecutor's statement referred to Ansar Bait al-Maqdis as "the most dangerous terrorist group,'' accusing the defendants of receiving military training in the Palestinian Gaza Strip under the patronage of Hamas.
The 200 are charged with carrying out dozens of attacks that have killed policemen and civilians. As of May 10, 102 defendants were in custody and 98 remained at large.