Al-Qaeda's front group in Iraq claimed a suicide car bomb against parliament in November which it said targeted Prime Minister Nuri al-Maliki and MPs, in a statement published on Monday.
The Islamic State of Iraq (ISI) also said it was behind a December 26 suicide car bomb against the interior ministry in Baghdad, as well as dozens of other attacks.
"The route was easy and we seized the opportunity to insert a car bomb driven by a hero from the (ISI) to enter the Green Zone," said a statement from the group posted on the jihadist forum Honein.
"His target was the head of the Iranian project in Iraq... to attack the head of the snake and some dirty representatives," it said.
An Iraqi lawmaker was wounded and two other people were killed in the November 28 attack, which various officials have said was a botched attempt to kill either Maliki or parliament speaker Osama al-Nujaifi.
Baghdad security spokesman Qassim Atta said last month that the attacker drove a black SUV containing 20 kilogrammes of locally-made explosives.
In its Honein statement, ISI also claimed a December 26 attack in which a suicide bomber rammed an explosives-packed car into the compound of the interior ministry in Iraq, killing five people and wounding 39 others.
That attack came amid a still-unresolved political impasse which stoked sectarian tensions, pitting the Shiite-led government against the main Sunni-backed political bloc.
Security officials regularly say that while Al-Qaeda is no longer as powerful as it was in 2006 and 2007, at the height of Iraq's sectarian war, it is still able to carry out spectacular mass-casualty attacks.