In political developments, Sunni politicians accused Shiite Prime Minister Nouri al-Maliki of refusing to share power, as Iraq came under pressure from its neighbors to include all factions in decision-making.
The strongly worded statement by the National Accordance Front, which has 44 of parliament's 275 seats, did not issue a direct ultimatum but was issued on the opening day of a major international conference on Iraq in the Egyptian Red Sea resort of Sharm el-Sheik in a bid to remind the world of what the group sees as the gross failings of al-Maliki's government.
The announcement of the death of al Qaeda propagandist Muharib Abdul-Latif al-Jubouri came after days of conflicting government reports that the top leaders of the terror group and its front organization — the Islamic State of Iraq — had been killed.
In other developments:
Chief spokesman Maj. Gen. William Caldwell said the military did not have the bodies of al Qaeda boss Abu Ayyub al-Masri or Islamic State leader Abu Omar al-Baghdadi and did not know "of anybody that does."
He said the confusion apparently stemmed from misunderstandings by Iraqi security forces as al-Jubouri's body was being transported in Baghdad after it was released to his tribe. But he played down implications that it was a symptom of a broader problem of communication between U.S. and Iraqi forces, saying instead it showed that the Iraqis were doing their jobs.
"They at least knew that they had somebody who was very significant," he said, adding that was "a very positive thing.""
The Islamic State of Iraq confirmed in an Internet statement that al-Jubouri, whom it called its official spokesman, had been killed, but it denied the death of al-Baghdadi.
Al-Jubouri was believed to have been deeply involved with the kidnapping of Jill Carroll, the Christian Science Monitor reporter who was released unharmed, and Tom Fox of Clear Brook, Va., one of four men from the Chicago-based peace group Christian Peacemaker Teams who was found shot to death in Baghdad on March 10, 2006. He was also involved in the kidnapping of two Germans in January 2006, Caldwell said.
Caldwell said al-Jubouri helped facilitate Carroll's transport from one location to another and was believed to be the last known person to have custody of Fox before he was killed. The newspaper later released a statement saying that Carroll didn't recognize a photo of al-Jubouri that was released by the military.
U.S. and Iraqi forces have stepped up operations against the terrorist network following a series of car bombings and suicide attacks that have killed hundreds in recent weeks despite the 11-week-old operation in Baghdad and surrounding areas.
At least 50 people were killed or found dead in Iraq on Thursday, including four in mortar attacks in different parts of Baghdad and two in a parked car bombing that also wounded more than 30 in the oil-rich northern city of Kirkuk.
Caldwell said 87 militants had been killed and 465 people of interest detained in 139 operations against the group in April.
He also said al-Jubouri had been working in Syria helping to smuggle foreign fighters and funds into Iraq until he returned to the country in September.
Al-Jubouri was killed during an operation dubbed "Rat Trap" about four miles west of the Taji, a town near an air base north of Baghdad, early Tuesday, Caldwell said. The body was identified by photos and DNA testing, he said.
Al-Jubouri was arrested in 2003 by the U.S. and freed a year later, Caldwell said. A man who claimed to be a relative said al-Jubouri, in his mid-30s and a father of four, deepened his involvement with insurgents. The relative spoke on condition of anonymity out of concern for his own safety.
The military said the body was released to his tribe after a positive identification, but Iraqi security forces had taken it back into custody along with the person transporting it at a checkpoint in Baghdad.
The body was released after the mistake was discovered, but it was seized again at a Sunni mosque in the western Ghazaliyah neighborhood by Iraqi troops, acting on a tip that al-Baghdadi was holed up there, military spokesman Lt. Col. Christopher Garver said.
Garver said he believed the body had been returned to the tribe for burial.
On Thursday, mourners gathered at al-Jubouri's house in Duluiyah, 72 kilometers (45 miles) north of Baghdad, as a huge funeral tent went up in the street, police said.
The Interior Ministry said earlier that al-Baghdadi had been killed and released photos of a bloated body in a wooden coffin in the back of a pickup truck that it said were of him. On Tuesday, officials said al-Masri had been killed by rivals north of Baghdad, but the body had not been recovered.
But Caldwell said the military could not confirm the deaths of either individual.
"We have nobody in our possession or know of anybody that does, alive or dead, that is going through any kind of testing or analysis at this point with respect to those two individuals," Caldwell said.
The U.S. Embassy statement gave no other details about Wednesday's attack that killed the four contractors in the Green Zone — two from India, one from the Philippines and one from Nepal.
The Green Zone houses the U.S. and British embassies, Iraq's parliament and other key government offices and is considered the safest area of the city despite occasional shelling.
Two Americans — a contractor and a soldier — were killed in March in a rocket attack on the area. Two suicide vests were found unexploded in the Green Zone less than a week after that.
The adequacy of security in the area also came into question after the April 12 suicide bombing in the parliament building's dining hall. One lawmaker was killed in the blast, which was claimed by an al Qaeda-led amalgam of Sunni insurgents.
On Wednesday, Rear Adm. Mark Fox, a U.S. military spokesman, said the latest round of Green Zone attacks appears to be part of a strategy by extremists "to score a spectacular hit or try to obtain some sort of a headline-grabbing direct hit."