Al-Qaeda's leader has released an audio recording calling on "all Muslims" to carry out lone wolf attacks against the US and the West. Ayman al-Zawahiri also dismissed the Islamic State's (Isis) caliphate as illegitimate but said the two groups could work together. In the recording posted on Sunday 13 September, the group's leader called for violent acts to "harm the countries of the crusader coalition". He said: "I call on all Muslims who can harm the countries of the crusader coalition not to hesitate. We must now focus on moving the war to the heart of the homes and cities of the crusader West and specifically America." He also encouraged young Muslims in the West to follow the lead of the Tsarnaev and Kouachi brothers, who carried out the Boston marathon bombings and Charlie Hebdo shootings in Paris, respectively. It was not clear when the recording was made, but references to former Taliban leader Mullah Mohamed Omar as being alive suggest it is at least two months old. Omar's death was announced by Afghanistan's government in late July. Zawahri repeated his condemnation of Isis, which broke away from Al-Qaeda after defying the Egyptian former doctor's orders by forming a caliphate in Syria and Iraq, and said the group made "big mistakes". But he also hinted there may still be room for co-operation between the two groups, urging greater unity between the terrorist groups. Al-Qaeda has found itself playing second fiddle to IS in the militant jihad world, with the former unable to match the latter's powerful social media presence. The audio recording is seen as Zawahri's attempt to perform a reboot to revive Al-Qaeda's relevance. The Egyptian, who replaced Osama Bin Laden, accused IS militants of sedition and insisted their most senior figure does not deserve to be 'caliph', or ruler. He said: "Despite the big mistakes [of IS], if I were in Iraq or Syria I would cooperate with them in killing the crusaders and secularists and Shi'ites, even though I don't recognise the legitimacy of their state, because the matter is bigger than that."

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