Isis child militant: Paris 'investigates possible link' between boy who shot Israeli-Arab 'spy' – and Toulouse killer Mohamed Merah

Merah killed three soldiers, a rabbi and three Jewish children

Intelligence service believe the fighter (R) was Sabri Essid and are investigating whether the boy is his son

Paris officials are investigating whether a child who appeared to shoot dead a man accused of being an Israeli spy has links to an al Qaeda-inspired gunman who killed seven people in March 2012.

Isis released a disturbing video purporting to show the death of Muhammad Said Ismail Musallam on Tuesday evening. The group accused Mr Musallam, 19, of being a Mossad spy, a claim his family strenuously denied.

In the video, a militant speaking in French praised attacks against Jews and condemned Mr Musallam as an “apostate spy”. The child then shot Mr Musallam in the forehead and body.

A French police source told Reuters the intelligence service believes the fighter was Sabri Essid, the half-brother of Mohamed Merah, who killed three soldiers, a rabbi and three Jewish children over a ten-day killing spree in Toulouse and filmed all of his murders. He was shot dead by police after a 36-hour stand-off at his flat.

The source said they were also trying to establish whether the child, who appears to be no older than 12, was Essid's son. The French Interior Ministry declined to comment on the video.

Interior Minister Bernard Cazeneuve said in May Merah's sister Souad was likely to have travelled to Syria with her children.

The video comes weeks after Isis supporter Amedy Coulibaly attacked a Jewish kosher supermarket and killed four people.

Additional reporting by agencies