A 10-year-old boy who fought alongside his uncle in a militia battling the Taliban has been shot dead in an apparent assassination.

Mullah Abdul Samad was a former Taliban insurgent who changed sides and became a police commander in the district of Khas Uruzgan.

His nephew Wasil Ahmad was reportedly declared a hero for leading an armed defence against a Taliban siege last year after his uncle was injured, firing rockets at insurgents from a roof.

"He fought like a miracle," Mr. Samad said. “He was successfully leading my men on my behalf for 44 days until I recovered."

Rahimullah Khan, Uruzgan's deputy provincial police chief, said Wasil was killed in Tirin Kot on Monday as he made his way to school. Unconfirmed reports suggest he was shot twice in the head.

On their website, the Taliban reportedly claimed responsibility for killing Wasil, who had been widely seen on social media wearing a helmet and uniform and carrying an automatic weapon.

The use of child soldiers is illegal in Afghanistan, but the charity Child Soldiers International says both government forces and insurgents have been recruiting minors for years.

According to the charity War Child, there are estimated 250,000 child soldiers in the world today, 40% of which are girls.

The Afghanistan Independent Human Rights Commission blame the boy's family, the government and the Taliban for the death.

"Possibly he took up arms to take revenge for his father's death, but it was illegal for the police to declare him a hero and reveal his identity, especially to the insurgents," spokesman Rafiullah Baidar said.

"One side made him famous and the other side killed him - both sides ignored the law and acted illegally."