At least 10 people have been killed in two suicide bomb attacks in the Iraqi capital, Baghdad.
Those killed by the blast are said to have included police recruits
The deadliest explosion left a big crater near a police academy and the oil ministry building, a frequent target for militants.
The blasts came as US Defence Secretary Donald Rumsfeld arrived in the restive province of al-Anbar on an unannounced visit to American soldiers.
The US is unlikely to cut troop numbers till Iraq holds polls in 2005, he said.
In Baghdad, an oil ministry spokesman said the bomb may have gone off early.
"The bomb apparently exploded prematurely at an intersection
in front of the academy. Most of the dead were passers-by,
including seven women," spokesman Assem Jihad said.
Mr Jihad said 17 people were killed altogether, but the figure was later revised down.
In a separate Baghdad explosion, a suicide bomber blew himself up near the culture ministry.
An American soldier caught in the blast died later of his injuries.
In another development, Iraqi militants are reported to have released 10 Turkish hostages they had held for over a month, Arab television station al-Jazeera said.
The Salafist Abu Bakr al-Seddiq Group released the hostages "after the Turkish company [employing them] stopped operations and totally pulled out of Iraq," it said.
There is no confirmation.
'Test of wills'
Mr Rumsfeld had breakfast with US marine commanders at the al-Asad airbase, 200km (125 miles) north-west of Baghdad.
He later told an audience of 1,500 US marines that the US and its allies were
engaged in a "test of wills" with Iraqi insurgents.
"They know they cannot defeat us militarily, but they are hoping they can win the test of wills," he said.
US troop levels were unlikely to fall before Iraq's elections, he said, adding he hoped the newly trained Iraqi security forces would eventually ease the burden on American forces.
Rumsfeld told troops they were fighting a 'test of wills'
Mr Rumsfeld last visited Iraq in May at the height of the Abu Ghraib prisoner abuse scandal, before a US-appointed interim Iraqi government took charge in Baghdad.
This is the defence secretary's first visit to al-Anbar province, the scene of heavy recent fighting between US forces and Sunni-dominated militant groups.
Mr Rumsfeld later flew to Baghdad, where he met senior US generals and officials.
He also met Iraqi Prime Minister Iyad Allawi for talks "about plans for the coming elections to make sure they happen and to make sure this country continues on a path to democracy".
US and Iraqi officials say they intend to hold polls early next year despite the risk that the process may be targeted by insurgents.
They recently announced plans for a major military offensive in areas that have become rebel strongholds.
A ceasefire appears to be holding in one such hotbed of resistance, the Baghdad district of Sadr City, after fighters loyal to radical Muslim cleric Moqtada al-Sadr reportedly agreed to disarm.
They are due to begin handing in their weapons on Monday, a process expected to be completed within five days.