BEIRUT — Al Qaeda’s leader has urged Sunni Muslims to spare no effort to join the battle in Syria, overthrow President Bashar Assad and set up Islamic rule in the country.

Ayman al-Zawahri called on Sunnis everywhere to devote their lives, money and expertise for the fight and prevent a US-allied government from taking over in post-Assad Syria.

He urged Sunnis to “rise above their differences” and fight expanding Shiite influence in Syria.

The message came in a new audio recording posted on Thursday on the Internet. Its authenticity could not be independently confirmed but the message was posted on a militant website commonly used by al Qaeda.

Al-Zawahri has repeatedly called for holy war in Syria and has blasted Lebanese Hezbollah militants and Iran for supporting Assad.