The sheiks were associated with the Anbar Salvation Council, which had taken up arms to help drive extremists of al Qaeda in Iraq from the western province of Anbar.
Iraq's prime minister quickly vowed renewed support for Anbar province's tribal leaders after the noontime explosion, which also wounded 27 people and devastated the ground floor lobby of the high-rise Mansour Hotel.
"We are sure that this crime will not weaken the will of Anbar sheiks," Nouri al-Maliki said in a statement.
The attack, in which 21 others were wounded, was just one in a surge of five suicide and other bombings Monday that killed at least 45 people across Iraq.
A man wearing a belt of explosives walked into the Mansour hotel's lobby, approached the group of sheiks meeting there, and detonated his bomb, said a police officer based at the hotel, who spoke on condition of anonymity.
The massive explosion sent concrete crashing down from the ceiling, shattering windows and tore through everything in its path, reports CBS News chief foreign correspondent Lara Logan.
Police identified four tribal leaders killed as former Anbar governor Fassal al-Guood, sheik of the al-Bu Nimir tribe, Sheik Abdul-Azizi al-Fahdawi of the Fahad tribe, Sheik Tariq Saleh al-Assafi and Col. Fadil al-Nimrawi, both of the al-Bu Nimr tribe. Three of al-Guood's guards also were killed, the police officer said.
"It was a great breach of security because there are three checkpoints, one outside and two inside," said hotel worker Saif al-Rubaie, 28, who witnessed the blast and said all the casualties were Iraqis, most employees in the reception area.
The council has been holding meetings in the hotel for months. The deal they reached to join the U.S. military's fight in Anbar province constituted a major blow against the al Qaeda in Iraq-led Sunni insurgency in the region.
The U.S. command has pointed repeatedly to the Anbar group and its opposition to al Qaeda as an example for other tribes to follow elsewhere in Iraq.
Al-Yasiri was also killed in the blast.
In a story
The Mansour, which also houses the Chinese Embassy and is the Baghdad home for a number of Iraqi parliament members, is just a half-mile from the heavily fortified International Zone, where the U.S. Embassy and Iraqi government offices are situated.
A noted Iraqi poet, Rahim al-Maliki, also was killed, said Iraqi Media Net, the government organization on whose television network al-Maliki appeared.
In other developments:
American troops share the post with the local police, on the main road in central Beiji.
Initial police reports spoke of a single truck bomb, but the U.S. command later said two car bombs detonated, damaging a police barracks and the outer wall of the joint station.
That was followed by an attack by at least 30 insurgents firing small arms and rocket-propelled grenades, the command said.
Iraqi police and U.S. paratroopers of the 82nd Airborne Division repelled the attack, it said.
About 45 minutes later, another suicide car bomb exploded at a joint U.S.-Iraqi army checkpoint in central Siniyah, nine miles west of Beiji, killing two Iraqi soldiers and wounding three others, an Iraqi army officer reported.
Eyewitnesses said a U.S. Humvee vehicle was damaged in the blast, but "there were no U.S. casualties in both incidents," said Spc. Brian Bucy, a spokesman for Task Force Lightning, the U.S. military command covering the Beiji area.
American aircraft quickly appeared over the Beiji area and attacked suspected insurgent targets, eyewitnesses said.
Earlier in the morning, a suicide car bomber struck a checkpoint near the governor's offices in the predominantly Shiite southern city of Hillah, killing at least eight people and wounding 31, police said.
It was the second such attack in Hillah in three days. A parked car packed with explosives blew up on Saturday in the center of the city, 60 miles south of Baghdad, killing two people.
Three of the eight killed in Monday's Hillah explosion were policemen, as were at least four of the wounded, said a spokesman for the provincial police department.
The attacker drove his car into a checkpoint that leads to the headquarters of the Babil provincial government.
Police officer Baha Abdul-Sadda, 21, said he saw a red sedan speeding toward the headquarters, surprising police at the checkpoint and on the building's roof.
"The suicide bomber took advantage of the early hour and intended to hit the metal barrier to get inside to hit the building, but the car exploded prematurely at the metal barrier," he said. Abdul-Sadda, who suffered a head injury when thrown against a wall by the blast, spoke from his hospital bed.
The blast damaged the concrete walls surrounding the main building and shattered glass, but relatively few people were in the area because of the early hour, limiting the casualties, the police spokesman said.
Hillah, the capital of Babil, has been the target of some of the deadliest car bomb attacks by suspected Sunni Muslim extremists in the four years of insurgency and sectarian killings in Iraq.