Hamza bin Laden in 2001, the last time he was photographed in public

A son of Osama bin Laden who is regarded as the most likely next leader of al-Qaeda has called for a new jihad to save Syria from the Assad regime.

A recording released overnight on jihadist social media accounts purports to be of Hamza bin Laden, who is about 28 years old, urging Sunni Muslims to fight “crusaders”, Shia and “international aggression”.

An al-Qaeda branch known as Hayat Tahrir al-Sham (HTS) largely controls Idlib province in northwest Syria, after defeating other rebel forces. It is part of a “de-escalation zone” negotiated by Russia, Iran and Turkey, but there are repeated rumours that either the Assad regime, Turkey or an alliance of states will soon begin efforts to drive HTS out.

“The cause of Syria is