Initial autopsy findings from the body of an east Jerusalem youth who Palestinians believe was kidnapped and killed by far-right Jews showed that he was burned alive, the Palestinian attorney-general is reported as saying.

"The direct cause of death was burns as a result of fire and it's complications," Mohammed Al-A'wewy was quoted as saying by Palestinian official news agency Wafa late on Friday.

Muhammad Abu Khdeir's charred body was found in a forest on the edge of the city Wednesday, one day after the funeral of the three Israeli youths who were kidnapped and later found dead in field near Hebron.