U.S. troops also took part in the operation, which started soon after evening prayers on Friday.
The security sweep was conducted at a mosque and other sites in Baghdad, as well as in Saddam Hussein's hometown of Tikrit, some 130 kilometers north of the capital.
The U.S. military said in a statement some of the suspects are believed to be part of an insurgent group responsible for the deadly bombing of a Shi'ite shrine in Samarra on February 22.
Shi'ite Shrines In Samarra
The Golden Mosque before the 22 February bombing (courtesy photo)
UNDER THE GOLDEN DOME: The Iraqi city of SAMARRA is the site of two major Shi'ite shrines. Consecrated in 852, the Golden Mosque is said to hold the remains of two Shi'ite imams: Ali al-Naqi and his son, Hasan al-Askari. A second shrine marks the place where the hidden -- or 12th -- imam, al-Mahdi, son of Hasan, went into hiding.
Imam Ali and Hasan were imprisoned in Samarra, the capital of the Abbasid Dynasty, by Al-Mutawakkil Ala Allah Jafar bin al-Mu'tasim (821-861), who is considered the last great Abassid caliph.
According to historical accounts, al-Mutawakkil felt threatened by the growing influence of Shi'ite Islam and Imam al-Naqi, who was based in Medina. Al-Mutawakkil thus brought Imam Ali and Hasan to Samarra in 848 and imprisoned them inside a military fort. Henceforth they became known as al-Askari (military) because of the location of their imprisonment.
Following al-Mutawakkil's death in 861, his successor had Imam Ali poisoned in 868. Hasan died in 874.
Imam Ali al-Naqi -- the 10th Shi'ite imam, commonly referred to as Imam Ali al-Hadi -- and his son, Hasan al-Askari, the 11th imam, are buried under the Golden Dome, which was a gift from Persian ruler Nasr al-Din Shah (1848-96). The dome's construction was completed in 1905. Also buried in the shrine are Hakimah Khatun, the sister of Imam Ali, and Nargis Kahtun, Imam al-Mahdi's mother.
The second shrine in the complex marks the place where Shi'a believe Imam al-Mahdi (b. 868), the 12th and final imam, went into hiding. According to Shi'ite tradition, Imam al-Mahdi, the son of Hasan al-Askari descended into a cellar under the present-day shrine and disappeared. Shi'a believe that he never died, and he will return on Judgment Day.
MORE: For more information on Shi'ite and Sunni sectarianism in Iraq, see: