"As for the revenge by the Islamic nation for Sheikh Osama, may Allah have mercy on him, it is not revenge for Osama the person but it is revenge for those who defended Islam."

Osama bin Laden was killed at his Pakistani hideout by US commandos in 2011 in a major blow to the militant group which carried out the September 11, 2001 attacks.

Documents recovered from bin Laden's compound and published by the United States last year alleged that his aides tried to reunite the militant leader with Hamza, who had been held under house arrest in Iran.

Hamza bin Laden, now in his mid-20s, was at his father's side in Afghanistan before the 9/11 attacks and spent time with him in Pakistan after the US-led invasion pushed much of al-Qaeda's senior leadership there, according to the Brookings Institution.

Introduced by the organisation's new chief Ayman al-Zawahiri in an audio message last year, Hamza bin Laden provides a younger voice for the group whose ageing leaders have struggled to inspire militants around the world galvanised by Islamic State.