A homicide car bomb wrecked three vehicles in a U.S. convoy near Abu Ghraib (search) prison Saturday, and insurgents fired seven mortar shells at the jail and used grenades to damage three armored vehicles in another American convoy in the area, Iraqi police said.

The U.S. military issued no immediate casualty reports in any of the incidents.

There were no other details on the damage inflicted around Abu Ghraib, a prison just west of Baghdad (search) that was the scene of the torture and execution of countless political prisoners under Saddam Hussein and the abuse of detainees by American soldiers after the dictator's ouster.

In the northern city of Mosul, meanwhile, coalition forces said they arrested two alleged leaders of the Al Qaeda in Iraq terrorist group.

The two — identified as Taha Ibrahim Yasin Becher, whose alias was Abu Fatima (search), and Hamed Saeed Ismael Mustafa, also known as Abu Shahed — allegedly headed Al Qaeda's organization in Mosul, the country's third-largest city.

A statement said the arrests occurred Sept. 5. It also said Abu Fatima took over as Al Qaeda's top-ranking operative in Mosul after one predecessor was captured in June and another was killed in August. He held the post for only 12 days, the statement said.

In Baqouba, 35 miles northeast of Baghdad, one man was killed and six wounded when a homicide bomber drove his car into an Iraqi army patrol.

U.S. troops raided two suspected Al Qaeda safe houses in the northern town of Ubaydi and found a car bomb, weapons, ammunition and bomb-making materials, the U.S. military said. During the search, American forces came under fire and killed one attacker.

Saturday's attacks came after three days of bombings and shootings in Baghdad and elsewhere in which more than 200 people were killed and 600 wounded.

In Friday sermons, some Shiite and Sunni clerics condemned the rash of insurgent attacks but also criticized the U.S.-backed Iraqi government and American forces, saying they have not improved security in the 21/2 years since the invasion that toppled Saddam.

Sheik Abdul-Zahraa al-Suwaidi, a Shiite, said the violence tarnished the image of Islam and Muslims. He said, however, that the continued presence of 140,000 U.S. soldiers is fueling sectarian tension.

"You have to know that Iraq will gain its security if the occupation troops leave this country," al-Suwaidi told worshippers in Baghdad's Risafaa district.

Iraqi and U.S. officials have attributed the spike in violence to efforts by the insurgents to derail the democratic process ahead of the Oct. 15 constitutional referendum.

Jordanian-born Abu Musab al-Zarqawi's Al Qaeda in Iraq said the bombing surge in Baghdad was revenge for a joint Iraqi-U.S. offensive against its stronghold in Tal Afar, a city near the Syrian border.

In other developments:

—Police in Iskandariyah, south of Baghdad, said they arrested 13 people suspected of participating in Friday's assassination of the mayor and his four bodyguards.

—In Baghdad, police found the handcuffed corpses of three unidentified men dumped near the Omar Bin Abdul-Aziz mosque. Sunni community leaders have accused the Shiite-dominated security forces of operating death squads, but the Interior Ministry has denied this.

—Armed gunmen in western Baghdad attacked a convoy of four trucks carrying food for the U.S. military. Two Sudanese drivers were killed, police and hospital sources said.

—Police in Samarra, north of Baghdad, said they found the body of an Iraqi contractor who worked for the U.S. military. The man was handcuffed, blindfolded and shot in the head, police Capt. Laith Muhammed said.

—In Qaim, near the Syrian border, U.S. jets reportedly bombed two houses overnight, killing one civilian and injuring another. The area along the porous frontier has been the target of repeated airstrikes in recent weeks, with the U.S. military saying it is trying to close off a prime infiltration route for guerrillas and foreign fighters.