A son of Osama bin Laden, al-Qaida’s slain founder, has urged Saudi Arabians to overthrow the kingdom’s rulers to free themselves from United States influence, the terrorism-monitoring company, Site Intelligence Group, has said.

In an undated audio message, Hamza bin Laden urged Saudi Arabian youth to join the Yemen-based al-Qaida in the Arabian Peninsula (Aqap) to “gain the necessary experience” to fight, according to Site.

Classified by the U.S. as the network’s deadliest franchise, Aqap was formed in January 2009 as a merger of the Yemeni and Saudi branches of al-Qaida.

Yemen is the ancestral home of Saudi-born Osama bin Laden, who was killed in Pakistan in 2011 by an elite team of US Navy Seals after a decade on the run.

U.S. intelligence officials have said that 23-year-old Hamza was the favourite son of the 9/11 mastermind who had been grooming him to take over as al-Qaida’s leader.

On the fifth anniversary of Osama bin Laden’s death – on May 2, 2011 – experts noted Hamza’s increasing prominence among jihadists in comparison with that of Egyptian al-Qaida leader Ayman al-Zawahiri.

A Saudi-led coalition is battling Iran-backed rebels in Yemen as well as Sunni jihadists who have joined Aqap and Islamic State.

Saudi Arabian authorities in 1994 stripped Osama bin Laden of his nationality after he issued fatwas, or Islamic religious pronouncements, denouncing both the royal family and the U.S.