Terrifying discussions about the royal family were discovered on secret messaging service Telegram, The Mirror reports.
The Star reported that the dire warning was posted to the encrypted app with a photo of Prince George at his Battersea school with the caption, "school starts early".
The threat also contained Arabic words from a song which translate to, “when war comes with the melody of bullets, we descend on disbelief, desiring retaliation”.
Concerns over security at George's school were raised when a woman filmed herself trespassing on the property and another was arrested for suspicion of attempted burglary.
The Metropolitan Police confirmed that security measured would be look at following the incidents.