The group, known as the Islamic State of Iraq, said in a statement posted on the Internet that the attacks in the Iraqi capital targeted the "bastions of evil and dens of apostates."
It also warned the group is "determined to uproot the pillars of this government" in Iraq and said "the list of targets has no end." The authenticity of the statement could not be independently verified, but it was posted on a Web site commonly used for militant messaging.
The blasts Tuesday were the third major strike against government sites in the Iraqi capital since August, raising serious questions about the abilities of Iraqi security forces ahead of next's year national elections and the withdrawal of U.S. combat troops.
Al Qaeda's claim gave renewed emphasis to U.S. military warnings that insurgents would likely continue high-profile attacks in an attempt to destabilize the Iraqi government in advance of the March 7 parliamentary elections.
The claim came as Prime Minister Nouri al-Maliki faced questions from lawmakers during a special session in parliament, where legislators have demanded answers over security lapses that allowed the attacks.
It appeared, though, that al-Maliki's top security chiefs would stay away. The prime minister arrived at the parliament without his interior and defense ministers, despite calls by lawmakers they appear as well to answer questions. The ministers have previously refused to attend two other sessions called after bombings on Aug. 19 and Oct. 25. More than 250 were killed in those attacks.
Lawmakers began the session early Thursday afternoon behind close doors.
Al-Maliki signaled the beginning of a possible security shake up late Wednesday after.
It was unclear whether the prime minister would announce any more changes in the leadership, although he has said Iraq's security strategies would be reviewed and further possible changes made.
Al-Maliki also was likely to offer an update on the bombings and security during a meeting later with U.S. Defense Secretary Robert Gates, whoThursday after wrapping up a three-day visit in Afghanistan.
Iraq has claimed al Qaeda and loyalists of Saddam Hussein's Baath party operating from Syria were behind the massive strikes in August and October, as well as the most recent bombings. Relations between the two countries soured after Baghdad accused Syria of harboring senior Baathists who masterminded the attacks. Syria has denied it.
While the U.S. military avoided comment Thursday on the validity of the bombing claim, it has said the August and October strikes bore the signature of al Qaeda. The group is known for suicide and vehicle-rigged bombings designed to inflict huge casualties that have tried to fuel sectarian tensions and push the country back to the Sunni-Shiite violence of 2006 and 2007 that brought Iraq to the brink of civil war.
A U.S. military spokesman in Baghdad, however, stressed that Iraq is in charge of safeguarding its people ahead of the national elections. "U.S. forces will provide security assistance for the elections as requested," said Lt. Col. Mark Ballesteros.
The three massive strikes in the Iraqi capital have differed from previous attacks because they hit government symbols and appeared aimed at having a far-reaching political impact, further undermining the government.
Al Qaeda also claimed responsibility Thursday in a separate Internet posting for last week's killing of Ahmed Subhi al-Fahal, known by al Qaeda and the American military as one of central Iraq's top counter-terror officials.
Al-Fahal, a lieutenant colonel in the Salahuddin provincial police force, was killed Dec. 3 in Saddam Hussein's hometown of Tikrit.
The posting said an Iraqi martyrdom seeker "strapped with his explosive belt and went looking for his prey and after long waiting and patience, his eyes met the criminal faces" and detonated his explosives among them killing him and four other officers with him.