Also, an American Marine was killed in action yesterday in Babel province south of Baghdad, the US military said, giving no further details.
The group led by Iraq's most wanted terrorist, Abu Musab al-Zarqawi, purportedly claimed responsibility in an Internet posting for at least one of the bombings -- as it had for a suicide car bombing on Monday that killed 125 people in Hillah, a town south of the capital.
''The bombings in Hillah and again in Baghdad this morning are not going to derail the political process that Iraq is embarked upon," national security adviser Mouwafak al-Rubaie said yesterday. ''The Iraqi government will go after and hunt down each and every one of these terrorists whether in Iraq or elsewhere."
But forming Iraq's first democratically elected coalition government is turning out to be a laborious process.
Shi'ite and Kurdish leaders, Iraq's new political powers, failed to reach agreement after two days of negotiations in the northern city of Erbil, with the clergy-backed candidate for prime minister, Ibrahim Jaafari, leaving with only half the deal he needed.
The Shi'ite-led United Iraqi Alliance, which has 140 seats in the 275-member National Assembly, hopes to win backing from the 75 seats held by Kurdish political parties so it can muster the required two-thirds majority for top posts in the new government.
Jaafari indicated after the talks that the alliance was ready to accept a Kurdish demand that one of its leaders, Jalal Talabani, become president.
''We, the United Iraqi Alliance, and I personally respect the Kurdish choice for Jalal Talabani to be their nominee for the presidential post. I will convey this honestly to my brothers in the alliance," he said.
However, he would not commit to other demands, including the expansion of Kurdish autonomous areas south to the oil-rich city of Kirkuk.
Kurdish leaders have demanded constitutional guarantees for their northern regions, including self-rule and reversal of the ''Arabization" of Kirkuk and other northern areas. Saddam Hussein relocated Iraqi Arabs to the region in a bid to secure the oil fields there.
Politicians had hoped to convene the new parliament by Sunday. But Ali Faisal, of the Shi'ite Political Council, said the date was now postponed and that a new date had not been set.