Imam Nadhum al-Mula Mahmud was arrested in the town of al-Dhiluya, north of Baghdad, on Sunday, our correspondent said.
He quoted witnesses as saying that occupation soldiers stormed Mahmud's house, accusing him of inciting anti-occupation attacks.
Two other people were arrested in the raid.
In related news, an Iraqi policeman was killed near the northern city of Kirkuk on Sunday after a police patrol came under attack, our correspondent said.
According to police, clashes broke out after the attack. Also in Kirkuk, two Iraqi civilians were wounded when two missiles fell near their homes, police said. The missiles were apparently aimed at a nearby US base.
In other news, a bus rammed a checkpoint in southern Iraq, wounding several people, including a Polish soldier as well as Iraqi troops and police, said occupation officials.
It was unclear why the vehicle failed to obey orders to stop, but US-led forces could not say whether it had been an attempted attack.
Speaking from Warsaw, Polish army spokesman Zdzislaw Gnatowski said a Polish soldier was hurt along with "several Iraqis" when the bus failed to stop at a checkpoint near Karbala, 110km south of Baghdad.
Polish troops opened fire on the bus as it continued driving towards the checkpoint, he said.
But, Gnatowski added, "It was not an attack."
Earlier, an occupation spokesman based in the area said the bus failed to stop after being ordered to do so.
"The bus hit the checkpoint and as a result it wounded a number of coalition soldiers, injured ICDC (Iraqi Civil Defence Corps) soldiers and civilians," he said.