BAGHDAD, Iraq (AP) – A leading Sunni cleric called for religious and ethnic groups to take a stand against violence as Iraq endured a third consecutive day of sectarian killings – the worst, a suicide car bombing at a Shiite mosque that killed at least 12 worshippers as they left Friday prayers.

The bombing in Tuz Khormato, where a young Saudi man was later arrested wearing a bomb belt on his way to a second mosque, was the latest suicide attack following al-Qaida in Iraq’s declaration of all-out war on Iraq’s Shiite Muslim majority.

Jordanian-born Abu Musab al-Zarqawi’s terror group said it was taking revenge for a joint Iraqi-U.S. offensive against its stronghold in Tal Afar, a city near the Syrian border.

With more than 20 people killed Friday, the death toll over the past three days surpassed 200, with more than 600 wounded.

Sheik Mahmud al-Sumaidaei, a leading Sunni cleric whose group is linked to the country’s insurgency, criticized militants for targeting civilians. He called for Iraq’s religious and ethnic groups to take a stand against further bloodshed.

“I call for a meeting … of all the country’s religious and political leaders to take a stand against the bloodshed,” al-Sumaidaei said during his sermon at Baghdad’s Um al Qura Sunni mosque.

“We don’t need others to come across the border and kill us in the name of defending us,” he declared, a reference to foreign fighters who have joined the insurgency under the banner of al-Qaida. “We reject the killing of any Iraqi.”

In Tuz Khormato, 130 miles north of Baghdad, authorities said the attacker detonated his explosives-packed car as worshippers flowed out of the Hussainiyat al-Rasoul al-Azam mosque, a Shiite Turkmen place of worship.

Police said 12 people were killed and 23 wounded in the bombing, which also destroyed 10 shops and eight cars.

“We were stepping out of the mosque and suddenly a big blast shook the ground,” said Mustafa Ali, a 63-year-old ethnic Turkmen who escaped injury.

“I saw many people scattered on the ground, drenched in their own blood. I wanted to ask the bomber, ‘Why did you attack those innocents who had prayed?”‘ he said.

Police Capt. Mohammed Ahmed said his men exchanged gunfire with another bomber before capturing him as he fled toward a second mosque. The man, who appeared to be in his early 20s, said he was from Saudi Arabia.

Friday’s bloodshed began early, when gunmen opened fire on day laborers in an east Baghdad Shiite district. Three workers died and a dozen were wounded in the drive-by attack.

In Haswa, 30 miles south of Baghdad, a car bomb exploded near an Iraqi police patrol, killing three officers and wounding four, said police Capt. Muthana Khalid.

Gunmen also stormed the house of the mayor in nearby Iskandariyah, killing him and four bodyguards.

Sheik Fadil al-Lami, the Shiite cleric at Baghdad’s Imam Ali mosque, was gunned down as he waited to gas up his car, said police Col. Shakir Wadi. Authorities also found the bodies of three people in the same Shiite district, including one Iraqi soldier.

American forces raiding insurgent strongholds in the Euphrates River valley, northwest of Baghdad, called in airstrikes on militant positions in a stepped-up effort to retake cities and towns in Anbar Province, which includes the fertile region along the Euphrates as it flows southeast through the country from Syria.

A U.S. Marine was killed in the insurgent bastion of Ramadi, the provincial capital, the military said. At least 1,898 members of the U.S. military have died since the beginning of the Iraq war in March 2003, according to an Associated Press count.

In the Euphrates region, U.S. jets destroyed an al-Qaida complex in Haditha before dawn Friday. The night before, warplanes struck an abandoned school in Karabilah, killing nine al-Qaida militants.

As Shiite and Sunni clerics condemned the rash of attacks, they also lashed out at the U.S.-backed Iraqi government and American forces, holding them responsible for the recent violence because they were unable to improve security in the country 21/2 years after the U.S.-led invasion that toppled Saddam Hussein.

At the United Nations, Iraqi Foreign Minister Hoshyar Zebari said he believes Iraq’s government is capable containing the the violence.

“There is no complete immunity against terrorist attacks or suicide bombers or people who are ready to blow up … car bombs or themselves and downtown markets or schools or to kill children,” he said.

More than 300 followers of the powerful Shiite cleric Muqtada al-Sadr traveled from Baghdad’s Sadr City to the Kazimiyah neighborhood, where a suicide bombing Wednesday marked the start of the latest bloodshed, killing 160 people as day laborers assembled to find jobs.

The Iraqi government was “responsible for the security deterioration, and (we say to them) if they cannot protect Iraqis, then let Iraqis protect themselves,” Hazem al-Araji, a senior al-Sadr aide, told The Associated Press.

Sheik Abdul-Zahraa al-Suwaidi, also a Shiite, said the violence had tarnished the image of Islam and Muslims, but he blamed the continued presence of 140,000 U.S. troops for 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.