Bombers killed 41 people in two strikes on Iraq's fledgling security forces on Thursday, stepping up a bloody drive to sabotage plans for US-led occupation to give way to Iraqi rule on June 30.
A suicide bomber blew up his white four-wheel-drive car at an army recruiting base in Baghdad, killing 35 people and wounding 138, in Iraq's deadliest single bombing since a suicide attack on the same target killed 47 in February.
Later on Thursday, a car bomb killed six paramilitary civil defence guards and wounded four near the town of Balad, north of the Iraqi capital, the US military said.
Oil exports, Iraq's economic lifeblood, remained paralysed on Thursday after sabotage attacks on pipelines in the north and south. But, oil official said some exports could resume on Friday after repairs to a pipeline to a Gulf terminal.
The bystanders and army volunteers took the brunt of the Baghdad blast, the city's third suicide bombing this week.
Iraqis hoping to join the nascent army were waiting outside the base when hot shrapnel scythed through the air.
"Suddenly there was a huge explosion. Ten or 15 others were on top of me on the street. I can't go back. No way," said a volunteer Ibrahim Ismail from his hospital bed.
"This was a cowardly attack. It is a demonstration again that these attacks are aimed at the stability of Iraq and the Iraqi people," Prime Minister Iyad Allawi said at the scene.
Visiting US Deputy Defence Secretary Paul Wolfowitz said Iraqi security forces would need "substantial help" for some time and US troops would stay in Iraq as long as necessary.
But an opinion poll conducted for the US-led authority since a prison abuse scandal became public found that 55 percent of Iraqis would feel safer if US troops left the country now.