Car bombs have killed at least 41 people in and around the Iraqi capital, with 35 dying in a single attack on an army recruiting centre in Baghdad.
Passing cars were caught in the explosion
A car packed with artillery shells was reportedly driven into a crowd of about 100 people queuing to volunteer outside the Baghdad centre.
Debris littered a four-lane road and at least one unexploded shell could be seen lying on the blood-stained road.
A second bomb killed six Iraqi troops north of the city, a US spokesman said.
Four other members of the Iraqi Civil Defence Corps were wounded when the car bomb went off near the town of Balad, about 80km (50 miles) from Baghdad.
Iraq's interim Defence Minister, Hazim al-Shaalan, promised to crack down on militants.
"We will cut off their hands and behead them," he said, pledging that Iraqi soldiers would lead the operations with only logistical help from the US.
Buried under bodies
The health ministry says 138 people were injured in the Baghdad blast, on the site of an old airport, many of them seriously.
MONTH OF BOMB ATTACKS
17 June - car bombs kill at least 41 in Baghdad and near Balad
14 June - 13 people, including five foreign contractors, killed in Baghdad suicide car bombing
13 June - 12 Iraqis, including four policemen, killed in Baghdad suicide car bombing
8 June - Nine Iraqis killed and 25 wounded in Mosul car bombing
1 June - 11 Iraqis killed and 20 others, including two US soldiers, injured in suicide car bombing near Baiji
"Suddenly there was a huge explosion," recalled volunteer Ibrahim Ismail from his hospital bed.
"Ten or 15 others were on top of me on the street. I can't go back. No way."
Yas Khudair, a member of the Iraqi security forces, said the victims were all "poor people trying to earn a living".
"They wanted to volunteer to support their families," he said. "There were no Americans nearby when the explosion took place."
The same recruitment centre was hit by a car bomb five months ago when up to 47 people died.
Fear of cars
The heavily fortified Muthenna airport in the west of the city is also used as a military base for US troops.
The BBC's Barnaby Philips in Baghdad says military installations connected with the new Iraqi security forces are being hit again and again as insurgents step up their resistance ahead of the 30 June transfer of power.
UK Foreign Secretary Jack Straw said the attack would not affect the handover.
"The transfer of power will take place. Iraqis will take control of their lives," he said.
Another of our correspondents in Baghdad, Dumeethra Luthra, reports growing unease on the streets as the deadline approaches.
Some members of the security forces have told her they are afraid every time they have to check a vehicle, scared that it might contain a bomb, scared that this may be the car that kills them.
In other developments:
- The UK says it is deploying more than 600 Royal Marine commandos to Iraq in a move described as a "routine adjustment".
- The Pentagon admits US Defence Secretary Donald Rumsfeld ordered an Iraqi prisoner to be held in custody in circumstances violating the Geneva Conventions.
- A Hungarian soldier is killed in a roadside explosion south of Baghdad. It is Hungary's first military death in Iraq.