A statement purported to be issued by the militant organization "Islamic State of Iraq" has claimed responsibility for Thursday's attack on the Iraqi parliament.

Carried on websites frequently used to dissemninate Sunni militant propaganda, the statement has the hallmarks of Islamic State of Iraq pronouncements, unlike an earlier online posting that also suggested the Islamic State of Iraq had carried out the attacks.

The statement proclaimed “the arrival of the heroic gallant brother, one of the knights of the Islamic State, may God hold him dear, to the heart of the Green Zone -- may God crown it in black -- the temporary seat of the rats of the unbelieving Parliament, to detonate his explosive belt in the midst of the gathering of the heads of unbelief.”

The attack was designed, "to strip away the heresies of the claimed Baghdad security “plan” that they have drummed up, and fed to the media -- worldwide," according to the online document.

“He stormed their meeting where they were hatching conspiracies against the Islamic State, may God hold it dear, and he detonated his explosive belt upon them while they were gathering.”

“Three, at least, of the so-called deputies were killed, and a large number of them were seriously injured. And the rest of the bats and rats went to their burrows in panic,” the document continues.

The group also said in its apparent statement that the claim of responsibility was delayed in order to allow the attackers to flee.

The Islamic State of Iraq is an umbrella organization claiming to establish a separate political entity governed by Islamic law in much of Iraq. It is led by a man known by the nom de guerre of Omar al-Baghdadi, and is known to be associated with al-Qa'ida.