Baghdad, Iraq ? The shadowy leader of the Islamic State of Iraq, an al-Qaida-inspired group that challenged the authority of Iraq’s government, was captured Friday in a raid on the western outskirts of Baghdad, an Iraqi military spokesman said.

Abu Omar al-Baghdadi was arrested along with several other insurgents in a raid in the town of Abu Ghraib, said Brig. Gen. Qassim al-Moussawi, spokesman for the Baghdad security operation. U.S. officials had no confirmation of the capture and said they were looking into the report.

Al-Moussawi said al-Baghdadi admitted his identity, as did another “of the terrorists” who confirmed “that the one in our hands is al-Baghdadi.”

The arrest of al-Baghdadi would be a major victory for U.S. and Iraqi forces in their fight against Sunni insurgents, especially the hard-core religious extremists who have shown no interest in negotiating an end to their struggle.

But some analysts have pointed out that the al-Qaida-linked extremists rebounded after the death in June of Abu Musab al-Zarqawi, the charismatic al-Qaida in Iraq leader who died in a U.S. airstrike in Diyala province.

The self-styled Islamic State of Iraq was proclaimed in October, when a militant network that includes al-Qaida in Iraq announced in a video that it had established an Islamic state in six provinces including Baghdad that have large Sunni populations, along with parts of two other central provinces that are predominantly Shiite.

Unlike al-Zarqawi, virtually nothing is known of al-Baghdadi, including his real name. It is widely assumed that the name al-Baghdadi was taken as part of a campaign to make al-Qaida appear more of a homegrown Iraqi movement rather than an organization dominated by foreigners.

In a tape released in November, al-Zarqawi’s successor, Abu Hamza al-Muhajir, called on Sunni Muslims to pledge their allegiance to this new state and said al-Baghdadi was “the ruler of believers” with al-Qaida in Iraq fighters under his command.

Since then, the trappings of an Islamic shadow state with al-Qaida as its base has been taking shape in some towns and cities of Anbar province where a government presence hardly exists, according to Sunni residents.

Residents of Sunni insurgent areas north and west of the capital have reported seeing handbills posted on walls in the group’s name warning against un-Islamic behavior such as drinking alcohol.

Some residents of Anbar say Islamic State members have on occasion publicly flogged men for other offenses such as wearing long hair or harassing women and provided cooking fuel to residents in areas where the Iraqi government has little presence.

In its numerous Web postings, the Islamic State refers to punishment meted out by Islamic courts, although it is uncertain if these meet any standard under Islamic jurisprudence.

Last weekend, the Islamic State posted an online video of the execution-style shooting of 18 Iraqi security troops kneeling on the ground near a citrus grove. The three-minute video claimed the 18 kidnapped government security forces were slain in retaliation for the alleged rape of a Sunni woman by members of the Shiite-dominated police in Baghdad.

A senior adviser to Prime Minister Nouri al-Maliki told The Associated Press that al-Baghdadi had been taken into custody. The adviser spoke on condition of anonymity because he was not authorized to release the information.