The car bomb went off near a checkpoint on the road to Baghdad international airport on Wednesday injuring nine Iraqis, medics and witnesses said.
The bomb exploded not far from the first US checkpoint on the airport road in south-western Baghdad, setting fire to a US military Humvee vehicle, the US military said in a statement.
"A vehicle-borne improvised explosive device exploded in western Baghdad near an airport checkpoint at about 8.30am (0530 GMT)," it said in a statement.
The statement added that no members of the US forces were hurt in the blast, but sources working at Baghdad airport told Iraqi journalist Nizar al-Samarrai there were dead and injured among US forces and civilians.
"This same site was hit by another explosion a month ago," al-Samarrai added.
In a separate incident in Baghdad a senior Iraqi oil ministry official was killed on Wednesday, interim Iraqi government officials said.
Husayn Ali, a director-general at the oil ministry, was shot dead as he left his home in southern Baghdad's Qadisiya district to go to work, interior ministry spokesman Colonel Adnan Abd al-Rahman said.
Jordanians taken captive
The snatching of US-military upport workers continued with five Jordanians, including four truck drivers taken captive in Iraq, officials said.
The incident happened as US-backed interim Iraqi Prime Minister Iyad Allawi continued a visit to the kingdom on Wednesday.
Jordan "will seize the opportunity of the presence in Jordan of Iraqi Prime Minister Iyad Allawi to make more efforts to win the release of the hostages", the Petra news agency quoted government spokeswoman Asma Khudr as saying.
US warplanes have bombarded
Falluja for weeks without end
Khudr added that two other Jordanians had come under fire in the Ramadi region west of Baghdad.
They were apparently transporting goods for the US military.
"One of them was injured and the other was detained," she said, citing their relatives.
After the abduction of a Jordanian businessman last month, Khudr advised Jordanian nationals against non-essential travel to Iraq, although she said the authorities could not prevent people from going to the country.
Earlier this year Jordan had also secured the release of several of its citizens who were abducted in Iraq through negotiations with influential tribes.
A 31-year-old Filipino male was captured, the Philippines Foreign Secretary Alberto Romulo said on Wednesday.
Speaking at a news conference, Romulo identified the captive as an accountant, Roberto Tarongoy, who he said was seized in Baghdad on Monday.
No one has yet claimed responsibility.
In another part of Iraq, US warplanes bombarded the city of Falluja overnight, destroying what the military says is an arms cache and a command post.
There was no immediate word on casualties of the strikes.
A US military statement said the first attack hit a weapons cache in south-eastern Falluja late on Tuesday night. The second, at dawn, struck a suspected command post in the same area.
The statement said US-led forces had come under attack several times since Monday from fighters using small arms, rockets or mortars, rocket-propelled grenades and roadside bombs.
The Iraqi prime minister says
force may solve Falluja's crisis
It said US marines would pursue offensive operations "until Falluja is free of foreign terrorists and insurgents".
The marines are preparing for an expected full-scale assault on both Falluja and Ramadi, another city west of Baghdad.
The offensive is part of a crackdown by the the US and its interim Iraqi government as preparations for elections in January.
These offensives have caused scores of civilian casualties and numerous deaths with major damage to homes and the infrastructure.