The leader of al-Qaeda's Iraq arm defiantly has rejected an order from the terror network's central command to stop claiming control over the organisation's Syria affiliate, according to a message purportedly from him that was posted online. The statement by Abu Bakr al-Baghdadi, who heads the Islamic State of Iraq, reveals a growing rift within al-Qaeda's global network. It also highlights the Iraqi wing's determination to link its own fight against the Shiite-led government in Baghdad with the cause of rebels trying to topple the Iran-backed Syrian regime. In the audio message posted online, the speaker identified as Baghdadi insists that a merger he announced in April with Syria's Jabhat al-Nusra rebel group to create a cross-border movement known as the Islamic State in Iraq and the Levant would go on. Al-Nusra is an al-Qaeda affiliate that has emerged as one of the most effective rebel factions in Syria. Its head, Abu Mohammad al-Golani, has rejected the takeover attempt by al-Baghdadi. Al-Qaeda's global leader, Ayman al-Zawahiri, has tried to end the squabbling and bring the local affiliates back in line. In a letter posted online by Al-Jazeera last Sunday, Zawahiri declared that the Islamic State in Iraq and the Levant would be abolished and that the Iraqi and Syrian groups would remain independent with Baghdadi and Golani as leaders of their respective branches.