According to reports, ten Iraqi officers and 20 gunmen have been killed in several hours of intensive fighting after insurgents attacked a police station southeast of Baghdad.
Some 50 policemen were said to have been wounded while 21 insurgents were said to have been arrested.
US gunships fired missiles in a bid to dislodge the insurgents besieging the police station in the Sunni town of Salman Ak.
Border closures
Meanwhile, the Iraqi government said it was closing the country's borders for five days, starting next week, in a move designed to boost security.
The government gave no specific reason for the closure.
The dates coincide with a major Shi'ite religious ceremony, which was attacked by multiple suicide bombers last year when more than 170 people were killed.
The Iraqi government has imposed special emergency laws since November in a bid to curb the insurgency. It has imposed curfews, closed borders and detained suspects without normal legal procedures.
Drivers trying to enter Iraq from Syria, Iran and Jordan say that many border crossings are already shut.
