Bayan Jabbor, the Interior Minister, ended days of speculation by saying that the authorities were sure he had been hurt five days ago. “We are not sure whether he is dead, but we are sure that he is injured,” Mr Jabbor said.

The confirmation of reports, which first circulated on the internet on Tuesday, coincided with a fresh announcement on an Islamic website that a deputy had been appointed to take over the running of alZarqawi’s al-Qaeda group in Iraq while the commander recovered from his injuries.

The announcement said that the group’s leaders had met and named Sheikh Abu Hafs al-Qarni as deputy leader “until the return of our sheikh [Zarqawi] safely”. Al-Qarni was described as “carrying out the hardest operations, and our sheikh would choose him and his group for the tough operations”.

Experts on Islamic militants believe that al-Qarni has served as al-Zarqawi’s military adviser and is the emir, or commander, of al-Qaeda’s military committee in Iraq. He is believed to be a Saudi national who has been closely involved in al-Qaeda’s bloody campaign, including suicide attacks against American and Iraqi forces, as well as Iraqi civilians, the beheading of Western hostages and the assassination of government officials.

Doubts were cast on the report, however, by a second statement released by Abu Maysara, al-Zarqawi’s usual spokesman, who first made the announcement about his injury. He denied changes to the leadership and even predicted that the group would have some good news to announce soon.

“You will hear what will make you happy, faithful brothers, and the allies of Satan will hear what will anger them,” his statement said.

The confused messages do seem to agree that al-Zarqawi has been injured, probably seriously. If so it would give a huge boost to US forces and the new Iraqi Government, which has been criticised for falling to curb the violence that has claimed more than 600 lives.

Al-Zarqawi, who trained in Afghanistan, was imprisoned in his native Jordan and was later anointed al-Qaeda’s commander in Iraq by Osama bin Laden, has become a legendary figure with a $25 million (£13.7 million) US reward on his head.

His tactics, which include blowing up Shia Muslim worshippers and beheading Western civilians such as Ken Bigley, the British engineer murdered last year, have won him huge notoriety.

The efficiency of his group is often overlooked. Al-Zarqawi’s assassins have killed key figures in the fledgeling Government by penetrating the Iraqi military and police. They are launching suicide bomb attacks at an almost industrial rate. In Baghdad alone this month some 30 such attacks have taken place — more than in the whole of last year. In each case a driver, normally a foreign volunteer, has to be trained, the bomb prepared and the target chosen. The operation requires money, planning and disciplined execution by scores of people.

Whether al-Zarqawi’s removal from the insurgency will have any long-lasting effect is unclear. Most insurgent groups are Iraqi Sunnis who operate in small cells outside al-Qaeda’s control. It is widely accepted that their campaign cannot be defeated militarily, only by a political solution that will lure the Sunni minority back into Iraq’s political process.

Even Ibrahim Jaafari, the Prime Minister, cautioned that Iraq’s insurgency could not be attributed to one man. “He [al-Zarqawi] represents an obstacle and he’s one of the causes of trouble in the country,” he said. “Our fight is not simply with that person, it’s about the network and phenomenon.”

Nevertheless, senior Iraqi government sources are clearly delighted with al-Zarqawi’s troubles and even speculated that splits could be exposed within the insurgency, particularly between the foreign fighters and their Islamic militant allies and the wider Sunni community angered by recent attacks that have claimed mainly Iraqi civilian victims, including Sunnis.

Laith Kubba, the government spokesman, said that members of the public were coming forward with information about the insurgents, and that “for sure” in the restive Anbar region of western Iraq residents were “absolutely fed up with the outsiders who are coming with their dogmatic language and see Iraq as their battleground”.

He said: “The tips are coming. There is public support. After the bombs in Baiji, Tikrit and Mosul a lot of people who wanted to participate in the political process realised that the enemy No 1 . . . is the Zarqawi people. I won’t be surprised if tips come come and people say, basically, get them off our backs and give us something in return.”

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