"The direct cause of death was burns as a result of fire," Mohammed al-A'wewy was quoted as saying.
The post mortem examination on Mohammed Abu Khdeir was conducted by Israeli doctors, with Saber al-Aloul, the director of the Palestinian forensic institute, in attendance.
The Palestinian official news agency Wafa quoted the attorney-general as saying that Aloul had reported fire dust in the respiratory canal, meaning the victim had "inhaled this material while he was burnt alive".
According to reports, Mohammad Abu Khdair, who had also suffered a head injury, had burns to 90% of the body.
Aggression against Palestinians doesn't only come from extremist settlers. Israeli forces have killed several Palestinians and arrested hundreds of others, including Hamas members and lawmakers, since three settlers went missing on June 12 before they were found dead later.
Israel has blamed Palestinians and Hamas movement for the incident without providing any evidence; while Hamas has strongly rejected having any links to the case.
Israeli Foreign Minister has called for an all-out war against the Gaza Strip which is crippling under a harsh siege imposed by the Israeli regime since 2007.
RA/SHI