Most of the casualties were young recruits waiting to join, according to medical and security sources.
Ambulances rushed the wounded to hospital as edgy Iraqi soldiers at the scene fired shots in the air amid pools of blood.
Another car bomb in eastern Baghdad aimed at a police patrol wounded 11, three of them policeman, and a third car bomb near a bank in the restive town of Mahmudiyah, south of Baghdad, left one killed and three wounded, said an interior ministry source.
A slew of other attacks against Iraqi security forces north of Baghdad from Duluiyah to the northern refinery town of Baiji killed at least 13 people, six of them civilians, according to security forces.
And the Medical City hospital in Mosul said it received 12 unidentified bodies in the past 24 hours, most of them shot in the head.
Jaafari confirmed his support for US President George W. Bush's decision not to set a timetable withdrawing foreign troops from the country as the US president vowed to finish the Iraq mission despite dwindling public support.
"Iraqis are battling terror on behalf of the whole world," Jaafari told reporters after meeting members of his dominant Shia parliamentary bloc.
"The Iraqi nation is giving its dearest and its blood to defend humanity."
Jaafari, who just returned to Baghdad after taking part in the Iraq conference in Brussels and meeting with Bush in Washington, urged the world to back Iraq financially and otherwise because democratic values and global security were at stake.
"If the democratic process fails in Iraq then the drums of danger will bang threatening all democracies. Car bombs can be exported everywhere," he said.
With the constant blows to the fledgling security forces in mind, Jaafari said US-led foreign troops should not leave Iraq until the country's forces were ready to stand on their own.
"We look forward to multinational forces leaving but the timing must take into account national interests and not be dictated by terrorists," he said. "The timing must be Iraqi."
A recent ABC News/Washington Post poll showed 53 percent of Americans now believed the war was not worth fighting.
Meanwhile, hundreds of Shias in Najaf beat their chests, slapped their faces and chanted slogans as they mourned the killing in Baghdad on Friday of Kamaleddin al-Ghuraifi, a senior aide to Shia spiritual leader Grand Ayatollah Ali al-Sistani.
Ghuraifi's killing was followed by the kidnapping of a Sunni cleric.
In another development that could stoke tension, Iraq's President Jalal Talabani demanded Kurds be allowed back to the contested city of Kirkuk, and Arabs sent there during the former regime's Arabisation drive resettled in their original homes.
"Jaafari's government must implement this immediately," Talabani told reporters during a visit to his native Kurdistan region in northern Iraq.
Moreover, US forces released Mohammed Tabtabai Hakim, an aide to Moqtada Sadr arrested and imprisoned more than a year ago, said a member of Sadr's movement.