The Iraqi authorities have hanged 13 people accused of taking part in the insurgency, the first execution of militants since the US-led invasion.
"The competent authorities have today carried out the death sentences of 13 terrorists," a cabinet statement said.
The name of only one of those executed was released. Shuqair Farid, a former policeman, allegedly confessed he had enlisted Iraqis to carry out attacks.
Three convicted murderers were hanged last September.
The US-led coalition abolished the death penalty in Iraq after the overthrow of Saddam Hussein, but it was re-instated during the handover to Iraqi control in June 2004.
The Iraqi government wanted to give itself the option of executing the former president, who is currently on trial with seven others for the killing of 148 Shias from the village of Dujail in 1982.
In October, the Iraqi Transitional National Assembly passed a new law which extended the use of the death penalty to include "those who commit... terror acts" and for "those who provoke, plan, finance and all those who enable terrorists to commit these crimes".
The assembly also approved a sentence of life imprisonment to "whoever intentionally conceals terrorist activity or gives shelter to a terrorist for the purpose of hiding him".
Iraqi President Jalal Talabani is opposed to capital punishment and refused to sign the death warrants of those executed in September, instead authorising his deputies to do so.
The BBC's Andrew North in Baghdad says that, with more than 14,000 people currently in US coalition detention, it raises the possibility that there could be many more executions.