The US-led coalition has paid an Iraqi informant $1m for a tip-off about the whereabouts of one of the men on the American list of "most-wanted" Iraqis.
Khamis Sirhan al-Muhammad: Number 54
Last month, US forces captured Khamis Sirhan al-Muhammad, a former regional Baath Party chairman and militia commander, in Ramadi, west of Baghdad.
Al-Muhammad was number 54 on the list of 55 former officials.
The coalition says his arrest is "a significant step forward" and proof that bounties of this kind are working.
"Less than a month following receipt of that tip we've approved payment of $1m to the Iraqi informant," coalition spokesman Dan Senor told a Baghdad news conference.
Al-Muhammad was "organising, facilitating and financing attacks against the coalition," Mr Senor added.
His arrest has left 13 out of the 55 most-wanted Iraqis still at large.
The reward offered for finding former Iraqi leader Saddam Hussein was $25m, but the US has not said whether they have yet made any payments to those who helped in his capture.
US soldier killed
Attacks against coalition forces and Iraqis working for the coalition are still occurring on a daily basis.
Tuesday saw one US soldier killed and another wounded when a roadside bomb exploded near Iskandriyah, some 60 kilometres south of Baghdad.
The blast took place during an operation to clear such bombs.
The day also saw three Iraqi police officers killed near the holy city of Karbala, south of Baghdad.
A police spokesman said gunmen opened fire with machine- guns from a passing carat the police vehicle - which blew up when a bullet hit the petrol tank.