Iraqi officials say a suicide bomber killed 40 Iraqis on Monday at a joint U.S.-Iraqi base north of Baghdad.
They say the bomber detonated his explosives at an army recruiting center near Tal Afar.
The attack came as Shi'ite ministers in Iraq's government criticized a U.S-Iraqi operation in Baghdad on Sunday that left 16 people dead. Several ministers say the raid killed unarmed worshippers at a mosque complex in the capital's Sadr City neighborhood.
But the U.S. military says Iraqi special forces, acting with U.S. advisors, killed insurgents and freed an Iraqi who had been taken hostage. The military also denied any troops entered the mosque.
Later Monday, unidentified gunmen kidnapped 16 employees of an Import Export company in Baghdad.
And Arab satellite television station al-Jazeera aired a videotape purportedly from Saddam Hussein's fugitive lieutenant, Izzat Ibrahim al-Douri, calling on Arab leaders to boycott the Iraq government and support the Sunni-backed insurgency.