Guerrillas fired rocket-propelled grenades at Iraqis queuing up outside an army recruitment centre in the northern city of Mosul on Saturday, wounding 17 people in the second such attack in a month.
"Unidentified assailants fired rocket-propelled grenades at a line of civilians waiting at the gate of the recruiting centre to get jobs in the new Iraqi army," army Captain Ahmad al-Deen said.
"Sixteen civilians have been wounded, as well as one security guard."
Guards said the attackers fired the grenades from a car before driving away.
Last month a mortar attack on the recruiting centre killed four people and wounded at least 15.
Anti-American guerrillas have frequently targeted Iraqis joining new, US-supervised security forces such as the police.
Saddam Hussein's 375,000-strong armed forces were disbanded after their defeat last year. But in anticipation of a return of sovereignty to an Iraqi interim government on June 30, US commanders are overseeing recruitment to a new army.
Iraqi group takes Kuwait driver hostage: Jazeera
An Iraqi Islamist group has taken hostage a Kuwaiti lorry driver taking supplies to US troops and warned Iraqis against co-operating with the "infidel occupiers", Al Jazeera television said on Saturday.
"The group warned all those who think of co-operating with what it called 'the infidel occupiers'," the channel said, showing a videotape it had obtained of the man.
In the tape, a large group of masked, armed men calling themselves the Waqas Islamic Brigade stand around the man, who gave his name as Saad Saadoun.
Saadoun said on the tape he was seized after "mujahideen" attacked his lorry near Baghdad while he was bringing supplies to US troops from Kuwait.
"I promise I will not do this again and I advise my brothers not to co-operate with the Americans," he said.
Al Arabiya television aired footage on Wednesday of an Iraqi group threatening to kill an Egyptian and a Turkish hostage if their countries did not condemn the US-led occupation in Iraq.