Islamic State video claims killing of 'Israeli Arab spy'
Islamic State (IS) militants have posted a video online which appears to show a young boy shooting dead an Israeli Arab prisoner.
The man, identified as Mohammed Said Ismail Musallam, was accused by IS of working for Israel's Mossad foreign intelligence service.
The 19-year-old left his home in East Jerusalem for Turkey last year, apparently intending to fight in Syria.
Israeli officials and Mr Musallam's family denied he was an Israeli spy.
The video footage has not been independently verified and Israeli officials said they could not confirm its authenticity.
Mr Musallam's family said he had left for Turkey four months ago without telling them. Soon after his departure, he told his brother that he planned to join IS in Syria.
A spokesman for the Shin Beth security service also told the AFP news agency that he had left home "on his own initiative".
At the scene: Yolande Knell, BBC News, East Jerusalem
Comforted by her remaining three sons, Umm Ahmed sits weeping for 19-year-old Mohammed Musallam.
She recalls her shock when she discovered that he had run away to join Islamic State fighters in northern Syria. "They recruited him through the internet," she says. "They told him: 'Come and we'll give you a house, money, you can get married - we have beautiful girls.'"
By the time Mohammed contacted his family from Raqqa late last year, the clean-shaven teenager had grown a beard and was carrying a Kalashnikov rifle. But his father says he had become disillusioned and wanted to return home.
Said Musallam tells me that Mohammed, an Israeli citizen, tried to escape but was caught and accused of being an Israeli spy.
"There was no way they were going to let him go," he says. "He'd been there for three months and seen their weapons. They said: 'He betrayed us, we'll ruin his reputation.' And that's what they did."
In February, the IS magazine Dabiq carried a long interview with Mr Musallam which contained what purported to be a confession that he had been sent by Israel to infiltrate the jihadist group.
The BBC's Kevin Connolly in Jerusalem says the article gave sketchy details about his alleged training and mission, but its publication was a clear signal that he had fallen foul of the group and was in clear danger.
On Tuesday evening, Islamic State's Furqan media outlet published a 13-minute video showing a young man, identified as Mr Musallam, sitting in a room wearing an orange jumpsuit, talking about how he was recruited and trained by Israeli intelligence.
He is later shown kneeling in an empty field, facing the camera. Behind him stand two figures in camouflage fatigues, one of whom appears to be a boy.
The boy appears to shoot the kneeling figure in the head with a handgun and then to fire further shots into the body.
The video then carries a warning from an older, French-speaking militant aimed at the Jewish people.
French media and IS supporters identified the older militant as Sabri Essid. He is reportedly a half-brother of Mohamed Merah, who killed three unarmed French soldiers, a rabbi and three small children at a Jewish school in France in 2012.