Iraqi troops have carried out house-to-house searches in the northern city of Mosul, as a new crackdown against al-Qaida in Iraq entered its second day Thursday.
It is unclear how many arrests took place.
Iraqi officials also eased some restrictions on movement that had been in force in Mosul.
Iraqi Prime Minister Nouri al-Maliki is overseeing the new offensive against al-Qaida militants in Mosul, their last Iraqi stronghold.
Iraqi officials say more than 500 suspected insurgents have been arrested in and around Mosul since the operation began earlier this week. The U.S. military says it is giving support to Iraqi troops leading the operation.
Meanwhile, the U.S. military says at least one militant was killed in overnight fighting in Baghdad's Sadr City.
The military says fighting in Sadr City between U.S.-backed forces and Shi'ite militiamen loyal to radical cleric Moqtada al-Sadr has eased in recent days.
Some information for this report was provided by AFP, AP and Reuters.