Troops secure the area of the motorcade bombing in Baghdad
The wife of Iraqi President Jalal Talabani has escaped unhurt after a bomb exploded near her motorcade in Baghdad, the president's office says.
Hiro Ibrahim Ahmed was travelling to a cultural festival at the city's National Theatre at the time.
Four of her bodyguards were injured in the attack.
Earlier, the US military said that a roadside bomb in Iraq's mainly Sunni western province of Anbar had killed four US marines.
The attack on Ms Hiro Ibrahim's motorcade occurred in the capital's Karrada district. It is unclear whether she was specifically targeted.
The president's office said: "One of the vehicles of Ms Hiro Ibrahim's convoy hit an improvised explosive device in the road this morning. She was heading to the National Theatre."
Ms Hiro Ibrahim is a daughter of Ibrahim Ahmed, one of the founders of the Kurdish Democratic Party, and married Mr Talabani in 1970.
The US has launched air strikes against Shia militias in Sadr City
She owns a media group and is a children's rights activist.
The US military has released no details of the exact location where the four marines were killed in Anbar province, which has seen some of the deadliest attacks on US forces.
The marines died when their vehicle was hit by an improvised explosive device, a US statement said. It said the attack took place on 2 May.
Elsewhere on Sunday, a woman journalist was dragged from her car and shot dead by gunmen in the northern city of Mosul, police said.
Serwa Abdul-Wahab was on her way to work when the attack took place.
Meanwhile, the Iraqi government announced on Sunday that it would set up a committee to fully investigate possible links between Shia militia groups and neighbouring Iran.
The announcement came after an Iraqi parliamentary delegation visited Tehran to discuss bilateral ties and clarify any involvement the Iranian military may have with Iraqi Shia fighters.
Since the end of March the Iraqi army, backed by US forces, has been fighting Shia militiamen in the Sadr City area of eastern Baghdad.
About 1,000 people have died, most of them civilians.
The US says the militias are receiving training and supplies from an elite unit in the Iranian Revolutionary Guards Corps, the Quds Force. Iran denies this.
Until recently, Iraqi Prime Minister Nouri Maliki has shown little interest in investigating the possibility of such links, preferring to keep relations warm with his powerful neighbour, says the BBC's Clive Myrie in Baghdad.
But the current campaign to try to disarm Shia fighters, particularly in Sadr City, seems to have caused a rethink, our correspondent says.