The Egyptian affiliate of Daesh has shared images online of what it claims was the beaheaded of two men caught spying for the army in the Sinai.

The Daesh offshoot presented one of those executed as a "spy for the military intelligence" services and the other as a "spy for the army."

The pictures posted on Twitter Thursday night were deemed authentic by U.S. monitor SITE Intelligence Group.

The militants are waging an insurgency in the Sinai and have killed hundreds of soldiers and policemen since the military overthrew Islamist president Mohamed Morsi in 2013.

The militants claimed responsibility for the crash of a Russian passenger plane carrying tourists over Sinai last October, killing all 224 people on board.