Al-Qaida's deputy leader sought to bolster the terror network's main arm in Iraq in a new video released Thursday, calling on Muslims to rally behind it at a time when the group is on the defensive, faced with US offensives and splits with other insurgent groups. Ayman al-Zawahri defended the Islamic State of Iraq - the insurgent umbrella group headed by al-Qaida - against critics among Islamic militant groups, saying it was a vanguard for fighting off the US military and eventually establishing a "caliphate" of Islamic rule across the region. Al-Zawahri, the top deputy of Osama bin Laden, called on Muslims to follow a two-pronged strategy: work at home to topple "corrupt" Arab regimes and join al-Qaida's "jihad," or holy war, in Iraq, Afghanistan and Somalia to fight and train "to prepare for the next jihad." The Egyptian militant did not mention last week's failed car bombing attempts in Britain, which British authorities are investigating for al-Qaida links. That suggested the video, posted Thursday on an Islamic militant Web site, was made before the events in London and Glasgow. Al-Qaida's declaration of the Islamic State of Iraq last year was a dramatic move aimed at staking out its leadership of Iraq's insurgency. Allying itself with several smaller Iraqi Sunni insurgent groups, it presented the Islamic State as an alternative government within Iraq, claiming to hold territory. The move quickly met resistance. Some Islamic extremist clerics in the Arab world said it was too soon to declare an Islamic state because the Islamic law qualifications were not yet met and argued that a true Islamic state is not viable while there are still US forces in Iraq. Several large Iraqi Sunni insurgent groups publicly denounced al-Qaida, saying its fighters were killing theirs and pressuring them to join the Islamic State. One group, the 1920 Revolution Brigades, has begun overtly cooperating with US forces and Sunni tribal leaders to attack al-Qaida. At the same time, increased US forces sent to Iraq this year are waging a number of offensives in suspected al-Qaida strongholds north and south of Baghdad and in western Anbar province, claiming to have captured and killed a number of significant figures in the group. The offensives have caused an increase in American casualties, but insurgent and militia attacks appear to have fallen in the past week. On Thursday, Baghdad was relatively quiet, with police reports of a policeman and a civilian killed in a shooting and bombing. A roadside bomb hit a police patrol in the northern city of Mosul, killing a civilian and wounding three police. Iraq's Shi'ite and Kurdish leaders on Thursday were trying to overcome a Sunni Arab boycott of the Cabinet of Prime Minister Nouri al-Maliki, which threatens to hold up a key new oil law. The United States is pressing hard for passage of the long-delayed oil law in hopes it will encourage Sunni support of the government. Al-Zawahri spent much of the unusually long video - at an hour and 35 minutes - defending the Islamic State, criticizing those who refuse to recognize it "because it lacks the necessary qualifications" even while he acknowledged it had made unspecified mistakes. "The Islamic State of Iraq is set up in Iraq, the mujahedeen (holy warriors) celebrate it in the streets of Iraq, the people demonstrate in support of it," al-Zawahri said, "pledges of allegiance to it are declared in the mosques of Baghdad." He said Muslims around the world should "support this blessed fledgling mujahid garrison state with funds, manpower, opinion, information and expertise," saying its founding brought the Islamic world closer to "establishment of the caliphate, with God's permission." He urged critics to work with the Islamic State "even if we see in it shortcomings," and said Islamic State leaders should "open their hearts" to consultations. "The mujahedeen are not innocent of deficiency, error and slips," he said. "The mujahedeen must solve their problems among themselves." Al-Zawahri appeared in the video - first reported by IntelCenter and SITE, two US-based groups that monitor militant messages - wearing a white robe and turban and, as he often does, took a professorial tone, making points by citing Islamic history and by showing clips of experts speaking on Western and Arabic media. He denounced Egypt, Jordan and Saudi at length. He warned Iraq's Sunni minority against seeing them as allies, saying they pretend to support the Sunni cause while allying themselves with the United States. If Saudi Arabia controls Iraq or Sunni regions of Iraq, "the Iraqis would then suffer the same repression and humiliation which the people suffer under Saudi rule under the pretext of combating terrorism - i.e., combating jihad and preserving American security," al-Zawahri said. The al-Qaida deputy also laid out an al-Qaida strategy, saying in the near-term militant should target US and Israeli interests "everywhere" in retaliation for "attacks on the Islamic nation" in Iraq, Afghanistan and Somalia. The long-term strategy calls for "diligent work to change these corrupt and corrupting (Arab) regimes." He said Muslims should "rush to the fields of jihad" in Iraq, Afghanistan and Somalia "to defeat the enemies of the Islamic nation" and for "training to prepare for the next jihad."