Shiite Muslim clerics urged their followers on Friday not to be drawn into sectarian war, while insurgents kept up suicide bombings and assassinations targeting Shiite civilians and religious and political figures.

The attacks killed more than 25 people and followed two days in which nearly 20 car bombs killed nearly 200 people in Baghdad, most of them Shiite civilians. Al Qaeda in Iraq, a radical Sunni Muslim movement led by Abu Musab Zarqawi that has vowed to provoke civil war in Iraq, followed the attacks with an Internet posting that declared "all-out war" on Shiites, now Iraq's politically dominant majority.

Friday's deadliest violence occurred in the town of Tuz Khurmatu, 40 miles south of the northern city of Kirkuk, where 14 people were killed when a suicide attacker blew up a car packed with explosives just outside a Shiite mosque. The attacker drove the car close to the mosque's entrance and detonated it as worshipers streamed out after Friday prayers, said Col. Abbas Muhammed Amin, Tuz Khurmatu's police chief.

Moments later, Iraqi police and Kurdish security forces in the town arrested an apparent suicide attacker wearing an explosive belt, Amin said, adding that the man was believed to be a Saudi. Farther north, in Mosul, a bomb killed Hikmat Hussein Ali Mosili, who was an aide to the influential Shiite clerics Grand Ayatollah Ali Sistani and Ayatollah Muhammed Saeed Hakim.

South of Baghdad, in the mixed Sunni-Shiite city of Iskandariyah, gunmen broke into the home of Mayor Amer Muhammed Khafaji, a Shiite, and shot him and four of his guards dead, according to a police spokesman for Babil province, Capt. Muthanna Ahmed.

A suicide car-bomber in the nearby town of Musayyib killed three policemen.

In Baghdad's heavily Shiite district of Sadr City, assassins killed Fadhil Amshani, a cleric and follower of Shiite cleric Moqtada Sadr, as he headed to the Sadr movement's office, said Qahtan Rubaie, a Sadr spokesman.

In the center of Baghdad, insurgents landed a mortar round inside the U.S.-controlled Green Zone for the third day running. There were no injuries, U.S. officials said.

In far western Iraq, U.S. Harrier jets killed nine suspected insurgents in strikes on an abandoned schoolhouse in the town of Karabilah, according to the U.S. military. Insurgents were using the school as a base and were seen firing mortars outside the building at the time of the strikes, the military said.

Shiite preachers addressed the violence in their Friday sermons.

In Sadr City, Abdul Zahra Swaiedi condemned "the mass killings and explosions that target innocents all over Iraq," saying they were meant to distort the image of Islam. Swaiedi accused American forces of supporting the attacks to justify the U.S. occupation. "No to terrorism, no to terrorism," Shiite worshipers chanted in response.

There was no call for retaliation. In Baghdad's Buratha mosque, which is linked to Iraq's main Shiite political party, the Supreme Council for the Islamic Revolution in Iraq, Dhia Edeen Ahmadi urged restraint in his sermon.

"The aim of this criminal wave of killing is to draw us into a sectarian war, but that shall not succeed," Ahmadi said.

He urged Shiites to stay focused on national elections on Oct. 15 and Dec. 15, when Iraqis are to vote first on a new constitution and then a new government. Shiites, who make up about 60 percent of Iraq's population, have strong hopes of seeing their aims prevail in the balloting.

"We know who they are. They are the thugs of the Saddam regime who are trying to avenge their loss after losing power and the nice, affluent life they had," Ahmadi said of the insurgents, referring to the decades when Iraq was ruled by Saddam Hussein's Sunni-dominated Baath Party. "But history will not go back. This is our destiny, and no matter how many are killed, whether hundreds or thousands, we shall not turn back."

Sarhan reported from Najaf. Special correspondent Bassam Sebti in Baghdad contributed to this report.

Iraqis walk past the scene of a suicide car-bombing outside a Shiite Muslim mosque in Tuz Khurmatu, in northern Iraq, where 14 people were killed.

A recent wave of attacks against has left nearly 200 dead in Baghdad.