The Islamic State of Iraq said in a statement that it targeted the National Security Ministry and an AsiaCell store last Sunday because they are an inseparable part of the Shiite-led government's crackdown on insurgents.
"Our squads targeted two dens of evil used as spying places by Iraqi security services," the group said in a statement posted on a website used by militants.
The statement said insurgents also bombed "the evil AsiaCell office in the Mansour area" in west Baghdad, describing the store as "part of the security system that is used by the crusaders' government to chase the mujahedeen (holy warriors) and spy on them."
The Islamic State of Iraq includes al-Qaida in Iraq and other allied Sunni insurgent factions.
An Iraqi security official said the government has arrested at least one suspect in the Sept. 19 bombings that came only minutes apart. Most of the victims were civilians.
The official spoke on condition of anonymity because the investigation is ongoing.
The insurgents' statement comes at a delicate time in Iraq, where the government is in stalemate for nearly seven months following March 7 parliamentary elections that failed to produce a clear winner. U.S. officials fear the political vacuum could complicate Iraqi efforts to fully take over security and possibly open room for insurgents to regain footholds.
Envoys from Prime Minister Nouri al-Maliki's bloc opened talks Friday in Iran with a self-exiled militant cleric in attempts to end Iraq's political impasse, aides said.
The outreach to Shiite cleric Muqtada al-Sadr is part of a web of meetings and dealmaking to find ways of forming a new government. March elections left Iraq divided between a Sunni-backed coalition and various Shiite groups supporting either al-Maliki or his rivals.
Al-Sadr, who has been based in Iran for several years, leads a political group that has opposed keeping al-Maliki in power. But it appears al-Maliki is seeking to court the anti-American cleric and others to turn back a bid by one of Iraq's vice presidents, Adel Abdul-Mahdi, to win Shiite support to become the next head of government.
Iraqi Ayatollah Kadim al-Haairi, who lives in Iran and has a strong Sadrist following, issued a statement calling for an end to the impasse and for the backing of the leader with the most Shiite support. Although he didn't mention any names, the statement was seen as a boost for al-Maliki.
"The faithful politicians need to present a united initiative and expedite the nomination of the person who can run the government to be the prime minister," al-Haairi said in a statement. "They cannot neglect the wish of voters."
A Sunni-backed coalition led by ex-Prime Minister Ayad Allawi narrowly defeated al-Maliki's Shiite-dominated bloc in the March elections, but no single group has pulled together enough support to name a new prime minister and start assembling a government.
In an interview published Tuesday in the pan-Arab newspaper Asharq al-Awsat, Allawi insisted that his group has the right to form the government and said al-Maliki's attempt to cling to power are a "goodbye to democracy in Iraq."
"If al-Maliki insists on staying, I think the country will head toward strong turbulence," Allawi was quoted as saying.
Associated Press Writers Brian Murphy and Lara Jakes in Baghdad contributed to this report.