Al-Qaeda chief Ayman al-Zawahiri has urged Syrian rebels to fight to establish an Islamic state in the war-torn country, in an audio message posted online on Sunday.
"Let your fight be in the name of Allah and with the aim of establishing Allah's sharia (law) as the ruling system," he said in his first message on the Internet since November last year.
Syrian President Bashar al-Assad's regime dismisses the rebels as "terror" groups and Al-Qaeda Islamists. Fears of extremist Islamism playing a growing role in the conflict have contributed to curbing efforts to arm the rebels.
"Do all that you can so that your holy war yields a jihadist Islamic state," said Zawahiri, adding that such a state would help to re-establish the Islamic "Caliphate" system of rule.
"The enemy has begun to reel and collapse," he said, referring to forces loyal to Assad.
The United Nations says more than 70,000 people have been killed in Syria's two-year conflict, which broke out after the army unleashed a brutal crackdown against dissent, turning the uprising into a bloody insurgency.