Two US soldiers were killed and 11 others wounded in a pair of car bomb attacks in southern Baghdad on Saturday, the US military said.
A first car bomb detonated around 3:30 p.m. (1130 GMT), injuring three American soldiers, while a second one killed three soldiers and wounded eight others half an hour later.
In the latter incident, the troops were travelling to the site of the earlier explosion when they were ambushed, said the military.
Local residents earlier said the convoys were attacked by home-made bombs.
Loud explosions were heard and plumes of smoke billowed over the airport road, a scene of frequent attacks against US army vehicles and Western civilian convoys.
Over 1,000 US soldiers have been killed, including 778 killed inaction, since the coalition army launched the invasion in March last year.
Hours after the incidents, a statement published on a website said a group led by al Qaida figure Abu Musab al-Zarqawi was behind the twin attacks.
Two members from the "martyrdom brigade" of the Tawhid wal Jihad (unification and holy war) carried out the attacks, said the statement.
Zarqawi, with a 25-million-dollar bounty on his head, is said to be the mastermind of a series of lethal attacks in Iraq. US army has launched intensive raids on suspect sites believed to be his hide outs.