At least 57 recruits and soldiers have been killed and 123 wounded when a suicide bomber blew himself up at an army recruitment centre in Baghdad on Tuesday.
The blast, one of the bloodiest this year, occurred two weeks before the end of the US combat mission in Iraq.
The site of the attack was an army base near Baghdad's central Maidan square, which used to be the Defence Ministry under Saddam Hussein, and was turned into an army recruitment centre and military base after the 2003 US-led invasion.
Suspected insurgents also launched an assassination campaign against judges in the Iraqi capital and a volatile province north of Baghdad.
The bloodshed added to tensions that have followed an inconclusive election more than five months ago which has yet to produce a new government.
Insurgents have been targeting Iraqi police and soldiers as they prepare to take full responsibility for security on 1 September, when the United States ends its combat mission.
US troop numbers will be reduced to 50,000 for a training mission before a full withdrawal planned for next year.