Elsewhere, a soldier in the U.S.-led coalition was killed and two others were missing after an attack on a checkpoint, the U.S. military said. The incident took place about 8 p.m. Friday near the town of Yusufiyah, some 12 miles southwest of Baghdad.

The bombing of the Buratha mosque, one of several attacks nationwide, was carried out despite a four-hour driving ban intended to prevent suicide car bombs during Friday prayers, the main religious service of the week.

Buratha's imam, a leading Shiite politician, blamed al-Qaida in Iraq for the attack. He said the terror group was trying to reassert itself after the death of its leader in a U.S. airstrike last week.

"Al-Qaida is trying to restore some respect after the killing of the terror leader Abu Musab al-Zarqawi by targeting one of the leading Shiite clerics, but they will fail," said the imam, Jalal Eddin al-Sagheer.

The imam, who was not injured, said the bombing came after guards found two pair of explosive-laden shoes outside the mosque. The guards entered the mosque and began searching everyone who had carried their shoes inside, he said.

When they approached the attacker, he detonated what would have been a third pair of explosive-laden shoes, he said.

"The guards discovered two pair of shoes full of explosives. That got them to start searching all the worshippers. When one of them tried to search the suicide bomber, he blew himself up," al-Sagheer said.

But the Interior Ministry, noting the scale of destruction, suggested the attacker may have detonated a vest rather than shoes. Police Lt. Thaer Mahmoud said the attacker was indeed wearing a suicide vest.

The device contained metal balls and fragments, according to an Interior Ministry police officer who could not be named because he was not authorized to speak to reporters. Metal balls and fragments could fit into either shoes or a vest.

AP Television News footage showed a large scorch mark in the middle of the mosque. Blood was spattered across the turquoise- and gold-trimmed tiled walls and white ceiling. The bomber was beheaded and dismembered by the blast, which Mahmoud said killed 13 and wounded 28.

It was the second attack on the Buratha mosque in just over two months. On April 7, four suicide bombers, including a woman, set off their explosives during Friday prayers, killing at least 85 worshippers. The U.S. military blamed al-Zarqawi.

Al-Sagheer, a member of Prime Minister Nouri al-Maliki's United Iraqi Alliance, said the terror group had threatened to kill him in an Internet posting this week. A similar warning preceded the April attack, he said.

He said al-Qaida accused him in the latest posting of being behind deaths squads targeting Palestinians living in Baghdad. Since the Saddam Hussein era, a large contingent of Palestinians, who are Sunni Arabs, has lived in Baghdad.

On Friday, Al-Jazeera aired an audio tape of a key insurgency leader calling the killing of al-Zarqawi a "great loss" but saying it will strengthen the militants' determination.

The broadcaster identified the voice as that of Abu Abdullah Rashid al-Baghdadi, the head of the Mujahedeen Shura Council, which groups five Iraqi insurgent organizations including al-Qaida in Iraq. The authenticity of the tape could not immediately be verified.

Significantly, the speaker does not mention the man identified by the U.S. as al-Qaida in Iraq's choice to replace al-Zarqawi ¡ª Abu Ayub al-Masri, also known as Abu Hamza al-Muhajer. The lack of such a reference may suggest that al-Baghdadi does not support him.

On Tuesday, al-Qaida in Iraq had issued a statement vowing to avenge al-Zarqawi's death and threatening horrific attacks. The next day, Iraqi authorities launched a security operation with 75,000 troops fanning out on the streets of Baghdad.

There has been a slight decrease in the number of Iraqis reported killed since al-Zarqawi died June 7. In the nine days before the airstrike, 307 Iraqis were killed compared with 262 in the nine subsequent days, according to an Associated Press tally.

The U.S. military said a "high-ranking terrorist network commander" linked to the deaths of at least seven coalition soldiers in roadside bombs was captured in the Shiite holy city of Karbala.

The suspect, identified as Sheik Aqeel, was captured by Iraqi soldiers who conducted a raid Thursday assisted by coalition advisers. They also seized another terror suspect and a substantial weapons cache, it said.

"Aqeel commands a Karbala terrorist network and is wanted for assassinating Iraqi citizens and planning and ordering attacks against Iraqi and coalition forces," the military said.

The 40-member local council in Karbala suspended its operations and demanded an apology Thursday after police said U.S. forces raided the house of council leader Aqil al-Zubeidi, a member of the Shiite Fadila Party, and arrested him and two other council members. Council spokesman Ghalib al-Daimi denied that al-Zubeidi had any links to terrorism.

Deputy Prime Minister Salam Zikam Ali al-Zubaie, responding to a news report, confirmed that Iraq has an agreement to take over security responsibilities from foreign forces in southern Iraq this month. Coalition troops would likely remain in the area with the Iraqis taking the lead.

In Baghdad, Deputy Justice Minister Busho Ibrahim said militias had infiltrated the Iraqi prison system. The justice ministry asked the U.S. to postpone transferring control of coalition detention centers to Iraqis until the problem is resolved. The U.S. reiterated it will not hand over such facilities to Iraqi authorities until they have demonstrated higher standards of care.

Lt. Col. Kier-Kevin Curry, a spokesman for U.S. military detainee operations, also said in an e-mail that Abu Ghraib will be transferred to the Iraqi government after the inmates there are moved to a new prison at Camp Cropper later this summer.

U.S. special operations forces fed some Iraqi detainees only bread and water for up to 17 days, used unapproved interrogation practices such as sleep deprivation and loud music and stripped at least one prisoner, according to a Pentagon report on incidents dating to 2003 and 2004.

The report, with many portions blacked out, concludes that the detainees' treatment was wrong but not illegal and reflected inadequate resources and lack of oversight and proper guidance more than deliberate abuse. No military personnel were punished as a result of the investigation.