Al Qaeda's umbrella group in Iraq claimed responsibility Thursday for coordinated Baghdad bombings this week that killed 127 people and wounded more than 500, warning of more strikes to come against the Iraqi government.

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.

SLIDESHOW: Baghdad Blasts

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.

Anger over Tuesday's security breaches forced Prime Minister Nouri al-Maliki Thursday to face tough questions from lawmakers in a closed session of parliament, where he deflected blame and accused political discord of jeopardizing Iraq's stability.

Lawmakers, who came out of an ongoing special session, told reporters the prime minister cast blame on rival political blocs that he says prevented him from appointing a chief of secret police as well as a lack of cooperation among security forces in Baghdad.

They said al-Maliki went so far as to blame a 2003 decision by the United States to disband the Iraqi army.

"His defense is not convincing," Sunni lawmaker Adnan al-Jibouri said.

Al-Maliki's top security chiefs stayed away from the session, 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.

Al-Maliki was expected to give an update on the bombings during a scheduled meeting later with U.S. Defense Secretary Robert Gates, who flew to Baghdad Thursday 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 homicide and vehicle-rigged bombings designed to inflict huge casualties.

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.

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's hometown of Tikrit.