Islamic State of Iraq (ISI) said in a message posted on Internet forums that it was behind attacks on Sunday at the Iranian, Egyptian and German missions, the US-based SITE Intelligence Group said late on Thursday. The attacks also wounded more than 200 people.
The group denied playing a role in explosions at seven residential buildings in Baghdad two days after the embassy bombings, SITE said. Those blasts killed at least 35 people and wounded more than 100.
Tensions have been running high in Iraq since a March 7 parliamentary election that failed to produce a clear winner.
The inconclusive poll promised weeks of potentially divisive talks between political blocs to form a new government.
Security forces had warned that violence could increase if a power vacuum ensued as politicians jockeyed for position.
Sectarian violence exploded when it took five months to form a new government after elections in 2005.
Overall violence has declined sharply in the last two years after the sectarian slaughter of 2006-07, but bombings and assassinations are still a daily occurrence.
The embassy and residential blasts, along with an attack on a village south of the Iraqi capital last Friday, prompted Prime Minister Nuri Al-Maliki to tighten security in the capital. He warned political leaders to work to prevent an escalation of the violence.
ISI called the attack the "fifth wave" of a campaign of mass-casualty bombings, SITE said. ISI is believed by intelligence analysts to have been created by Al-Qaeda in Iraq as a local umbrella group for insurgent organizations.
ISI said any embassy or political organization that provided support to the Iraqi government could be put at the top of a list of targets that "the mujahideen will not hesitate to strike, wherever its location and no matter the level of its fortification,” SITE said.
The group warned Iraqi voters before the parliamentary election that they risked death if they cast ballots. About 62 percent of registered voters turned out at the polls despite the threats and election day violence that killed 39 people.
ISI has claimed responsibility for numerous attacks. They include bombings at three Baghdad hotels in January that killed at least 36 people and attacks on government buildings in December that killed 112.
