10-year-old Ali Daqneesh succumbed to his injuries at hospital.
The older brother of Omran Daqneesh, a Syrian boy who was pictured sitting in an ambulance dazed and covered in blood after an air strike in his hometown of Aleppo, died Saturday from wounds sustained in the attack on the family's apartment, a monitoring group said.
Confirming death of 10-year-old Ali Daqneesh, the Syrian Observatory for Human Rights said, "He succumbed to his injuries. He was badly wounded in the same bombardment as Omran on August 17 in Aleppo."
The haunting images of four-year-old Omran, sitting in an ambulance after the attack, his face, arms and legs caked in blood and dust, have reverberated around the world, becoming a symbol for the suffering of children in Syria's brutal five-year conflict.
Omran, in video footage from the incident, is seen quietly staring into space before raising his arms to touch his bloodied forehead, then looking at his hand and wiping it on the orange seat.
Omran, his siblings and parents were all plucked from the rubble wounded, but alive, following Wednesday's bombing on the Qaterji neighbourhood in east Aleppo.
The Aleppo Media Centre confirmed Ali's death in a video on Saturday.
Omran survived & brought tears to our eyes, but his brother Ali who died today represents the real suffering. pic.twitter.com/37wgcPKOXg— Kenan Rahmani (@KenanRahmani) August 20, 2016
The images of Omran have sparked a global outcry, much like the photo last September of three-year-old Syrian boy Aylan Kurdi, whose body washed ashore on a Turkish beach as his family tried to reach Europe.
More than 290,000 people have been killed since Syria's conflict broke out, including nearly 15,000 children.