The child's mother shared his picture online
The child's mother shared pictures of him wearing fatigues and carrying weapons on Facebook before he was killedSVT

A three year-old being trained as a child soldier - known as Caliphate Cubs - in Syria has been killed while reportedly playing with a hand grenade.

The Swedish broadcaster SVT reported that the child, brought to an Islamic State-held region of Syria by his mother from western Sweden when he was just two, tripped while playing with the grenade and was then blown up.

One of the toddler's older siblings was injured in the blast and witnessed his younger brother's death. Neither the identities of the two children nor their mother have been divulged.

In a series of images shared by the family from the Islamic State (Isis), the boy appears holding a variety of weapons including a replica Kalashnikov and other small arms. In another picture the boy is shown sleeping next to a rifle.

The boy is seen to wear military fatigues in bed, which is a common feature of Isis (Daesh) propaganda on child soldiers. The name Caliphate Cubs, which is used for child soldiers shown in Islamic State propaganda, takes its queue from Saddam Hussein's regime in Iraq.

Iraqi child soldier units under the Saddam regime were known as the Ashbal Saddam (Saddam's Lion Cubs). Created after Iraq's defeat in the 1991 Gulf War when Saddam was attempting to reconsolidate his power, the Ashbal Saddam recruited boys aged 10 to 15.

Swedish authorities estimate that anywhere between 120 Swedish men and women have joined IS. Many of those who have travelled to the area have taken their children with them while others have given birth in the country. A rough estimate shows that there are at least 60 Swedish children in IS territory, According to SVT.

After Belgium, Sweden has the second highest number of combatants per capita from Europe fighting for the Islamic State. In 2014, head of the Swedish Intelligence Service Anders Thornberg, said of the hundreds of reported cases of radicalised Swedes campaigning in the name of Isis, more Swedish citizens were believed to have gone to the Middle East – at around 32 fighters per million of the population.

"A hundred cases of people who have left to join the fighting have been confirmed. Then there are the presumed cases and then there are those who have not been counted," Thornberg told Swedish public radio.

In February, Kurdish Special Forces announced they had rescued Swedish national, Marlin Stivani Nivarlain, a 16-year-old from Boras. She had been rescued once, while heavily pregnant and was able to return to Mosul to give birth to her child.

The father of the child is believed to be the same 19-year-old with whom she travelled to Syria and then Iraq to join the Islamic State in June 2015.