BAGHDAD - A bomb planted near a Baghdad mosque killed three Shiite worshippers as they were leaving Friday prayers, Iraqi officials said, as Sunni and Shiite preachers condemned a draft security pact with the United States.

Police and health officials said seven people were wounded in the blast, which occurred in the primarily Shiite neighborhood of Shaab of north Baghdad.

Maj. Mark Cheadle, a U.S. military spokesman, said the bomb went off across the street from the mosque. He said three civilians were wounded but none died in the attack, which he blamed on Shiite extremists

Iraqi police and hospital officials gave the higher death toll but spoke on condition of anonymity because they were not supposed to release the information. Such conflicting casualty tolls are common in Iraq.

Throughout the country, mosque preachers used the weekly prayer services to speak out against the draft security agreement, which would allow U.S. troops to remain in Iraq until at least the end of 2011.

The government of Prime Minister Nouri al-Maliki is preparing to submit the draft to parliament for final approval - which U.S. officials believe is by no means certain.

In Najaf, an aide to anti-American cleric Muqtada al-Sadr told worshippers that the Sadrist movement would continue to oppose the deal "whatever the concessions that the government claims to have gotten."

The aide, Sheik Assad al-Nasseri, spoke one day before the Sadrists planned demonstration in Baghdad to drum up opposition to the deal.

In Baghdad, Sunni cleric Abdul-Sattar Abdul-Jabar said the agreement is "more dangerous than the occupation" and demanded the government refuse to sign it. He called for a referendum to allow voters to decide on the deal.

At another mosque, Shiite cleric Sadralddin al-Qubanji said the talks had taken place in secret and Iraqis were unaware of the details. He said the deal "might be negative or positive" and that the country stood at a "momentous turning point" in its history.

"There is no national unanimity about it," al-Qubanji said. "We cannot sign an agreement with secret terms."

Al-Maliki has said there are no secret parts although the government has not published the full text in Iraqi media.

Also Friday, Muslim clerics 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-Qaida 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.

Al-Qubanji said he disapproved of the attacks in "letter and spirit," adding that the violence represented a "malicious scheme against Christians and all Iraqis."

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. troop buildup, a U.S.-funded Sunni revolt against al-Qaida and a Shiite militia cease-fire.