BAGHDAD (AP) – A bomb planted near a north Baghdad mosque killed three Shiite worshippers as they were leaving Friday prayers, officials said, as Iraqi mosques used the holy day of the Muslim week to address a recent spate of attacks against Christians.

Police and health officials said seven other people were wounded and some homes also were damaged in the blast in the primarily Shiite neighborhood of Shaab.

The wounded were taken to Baghdad’s Kindi and Medical City hospitals, according to police and health officials, who spoke on condition of anonymity because they were not authorized to disclose the information.

Maj. Mark Cheadle, a U.S. military spokesman, said it was a “roadside bomb attack detonated on a vehicle across from the mosque.” He said three civilians were wounded but none died. Such conflicting casualty tolls are common in Iraq. “This has the signature of a Shiite extremist attack,” Cheadle said.

Inside mosques, preachers spoke of the plight of Christians in the northern city of Mosul, where thousands have fled amid attacks by suspected Sunni insurgents.

The recent series of killings, widely blamed on al-Qaeda in Iraq, have occurred as the Christian leaders stepped up lobbying efforts to ensure its representation in upcoming provincial elections in the primarily Islamic country.

In Iraq’s Shiite holy city of Najaf, cleric Sadralddin al-Qubanji said he disapproved of the attacks in “letter and spirit.” He said the violence represented a “malicious scheme against Christians and all Iraqis,” but also faulted the absence of government authority in the city. Islamic extremists have frequently targeted Christians and other religious minorities since the 2003 U.S.-led invasion, forcing tens of thousands to flee Iraq. However, attacks declined as areas became more secure after a U.S. troops buildup, a U.S.-funded Sunni revolt against al-Qaeda and a Shiite militia cease-fire. Sunni Sheik Omar Mohammed said forced conversion had no place in Islam. “We denounce the operations against the Christians in Mosul,” he said at a Baghdad mosque. His sermon also touched on a security deal that has been worked out between Baghdad and Washington governing the continued presence of American troops in Iraq. The agreement, reached after months of tortuous negotiations, would allow U.S. troops to remain here after their U.N. mandate expires Dec. 31. It is critical to ensuring Iraq’s security until government forces are capable of taking charge of the fight against insurgents.

A draft has been completed and the government is preparing to submit it to parliament for final approval, which U.S. officials believe is by no means certain.

Iraq’s prime minister recently sought the support of Grand Ayatollah Ali al-Sistani, but clerics throughout the country could prove influential in an eventual vote. “We reject the security agreement being plotted behind closed doors,” Mohammed said.

Al-Qubanji also criticized the lack of transparency of the U.S.-Iraq talks, but said the deal “might be negative or positive” at a “momentous turning point in the history of Iraq.”

The agreement includes a timeline for U.S. withdrawal by 2012 and a crucial compromise that gives Iraq limited ability to try U.S. contractors or soldiers for major crimes committed off-duty and off-base. “Iraqis do not know the articles of the agreement. There is no national unanimity about it and no transparency,” al-Qubanji said. “We cannot sign an agreement with secret terms.”