In Baghdad, meanwhile, three car bombs struck mostly Shiite areas Sunday evening, killing at least 25 people and wounding 51, police reported. The attacks appeared aimed at reviving sectarian tensions that once threatened to the nation with civil war.
Parliament last week approved a new law mandating elections in most of Iraq's 18 provinces. But the law removed a system that reserved a few legislative seats for Christians and other religious minorities.
Lawmakers cited a lack of census data to determine what the quotas should be. But many Christians saw the move as an effort to marginalize their community.
"I think that some political groups are pushing the remaining Christians to leave Iraq," worshipper Afram Razzaq-Allah said after services at a Catholic church in Baghdad. "They want us to feel that we are no longer Iraqis."
In a letter sent to parliament Sunday, Prime Minister Nouri al-Maliki appealed to the legislators and the electoral commission to restore the quota system.
"The minorities should be fairly represented in the provincial councils and their rights should be guaranteed," al-Maliki wrote.
Hundreds of Christians staged street protests after Sunday church services in and around Mosul, a northern city where many of the country's Christians live. Some said the removal of the quotas is an attempt to force them to leave Iraq.
"This is an unjust decision and it affects our rights as Christians," Matti Galia, a local politician, said at a rally in Mosul. "We are original citizens in this country. The politicians' goal was to divide the Iraqi people and create more struggles. Indirectly, they are telling us to leave Iraq."
Iraq's Christians have been targeted by Muslim militants since the U.S.-led invasion in 2003, with priests, churches and Christian-owned businesses attacked. The violence has led many Christians to flee the country.
Sectarian violence has receded since U.S. troop reinforcements were sent in last year. However, U.S. commanders have warned that extremist groups such as al Qaeda in Iraq are still trying to rekindle sectarian warfare to undermine the U.S.-backed Iraqi government.
The string of car bombings in the capital Sunday began near sundown as Muslims were preparing for Iftar, the meal that breaks the fast during the holy month of Ramadan.
The deadliest blast occurred in the Karradah neighborhood, where a parked car loaded with explosives blew up in a commercial area about 7 p.m., killing 12 people and wounding 34, police and hospital officials said.
About 90 minutes earlier, two car bombs exploded nearly simultaneously in the Shurta Rabaa and Amil districts of west Baghdad, police said. A total of 13 people were killed and 37 were wounded in the two explosions, police officials said. They spoke on condition of anonymity because they were not supposed to release the information.
Also Sunday, snipers fired on an Iraqi army checkpoint, killing two soldiers and a civilian in the eastern Zayona neighborhood of Baghdad. A roadside bomb killed an Iraqi soldier on a patrol in Mansour, a mostly Sunni area in the city's west, police officials said.
Two civilians were killed in an armed attack in the town of Khan Bani Saad by a group believed tied to al Qaeda, a police official in Diyala province said. The town is near the provincial capital of Baqouba.
The same official said two Iraqi soldiers were killed and 10 wounded when a bomb targeted them in Balad Ruz, 45 miles northeast of Baghdad late Saturday. A medic at the Balad Ruz hospital said the wounded suffered burns and shrapnel wounds and were later taken by U.S. soldiers to a military base.
Also Sunday, an Iraqi official said the country signed preliminary deals with General Electric Co. and Siemens AG to upgrade the electricity grid, which has been ravaged by years of war, sanctions and neglect.
Electricity Ministry spokesman Aziz Sultan said GE will supply turbines to some of Iraq's power plants. He said Iraq has also signed a similar memorandum of understanding with a third company but he had no details about it.
Lengthy power outages have been common in Iraq, with some Baghdad areas getting as little as four hours of electricity a day. The problem has been a major cause of discontent during the summer when the heat is punishing.
By Associated Press Writer Sameer N. Yacoub; Associated Press writers Qassim Abdul-Zahra and Bushra Juhi contributed to this report