The Iraqi commander of the Baghdad security crackdown announced Tuesday that Iraq will close its borders with Syria and Iran for 72 hours as part of the drive to end the violence that has threatened to divide the capital along sectarian lines.

Lt. Gen. Abboud Gambar, addressing the nation on behalf of Prime Minister Nouri al-Maliki, also said Baghdad's nighttime curfew would be extended by one hour and permits issued to civilians to carry weapons in public would be suspended for the duration of the operation.

Gambar did not say when the borders would be closed, but a government official said it was expected to happen within two days.

The announcement came hours after a suicide truck bomber struck a government warehouse in a mainly Shiite neighborhood, killing at least 15 people and wounding 27, according to police and hospital officials.

A parked car bomb also exploded near a bakery in another predominantly Shiite area in southeastern Baghdad, killing four people and wounding four, police said.

Gambar said one border crossing into Iran — near the southern city of Amarah — would not be fully reopened for another two months.

The United States has long charged that Iran and Syria were allowing militants to use their territory to slip into Iraq to attack U.S. and Iraqi forces, as well as civilian Iraqi Shiites. Iraqi authorities have routinely echoed the U.S. charges against Syria, but they rarely accused Iran of the same.

The U.S. military in Iraq this week said Iran was arming Shiite militants with sophisticated armor-piercing roadside bombs that have killed more than 170 members of the U.S.-led coalition forces. Iran maintains close relations with most of Iraq's Shiite leaders.

Gambar said Baghdad's nighttime curfew would be extended by one hour when the security drive kicks off fully starting from 8 p.m. and ending at 6 a.m.

The U.S. military announced last week that the security operation had already begun, although Iraqis have seen little evidence. Al-Maliki has aid the operation has yet to begin, a difference which appeared largely one of semantics.

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President George W. Bush has committed an additional 21,500 American troops to the security plan, which is widely seen as possibly the U.S. military's final attempt to placate the capital.

It would be the third attempt by U.S. forces and their Iraqi allies to end the violence in Baghdad since al-Maliki came to office in May 2006. A total of 90,000 Iraqi and U.S. troops were expected to participate in the drive.

Gambar's address suggested Iraqi authorities planned to exercise wide-reaching powers to ensure the success of the plan. A criminal court, for example, would hold emergency hearings to rule under Iraq's anti-terrorism law on cases such as murder, theft, rape, kidnapping, damaging public property or the possession and transfer of arms and ammunition, he said.

He said security forces would try to avoid going into places of worship, adding they would do so in "cases of extreme emergencies when it is feared that these places pose a threat to the lives of citizens or if they are used for unlawful purposes."

U.S. and Iraqi authorities have often said Sunni insurgents used mosques to store arms or fire at troops.

Gambar, a Shiite and a veteran of the 1991 Gulf War when he served in Saddam Hussein's army, said security forces also planned to monitor mail, parcels, telegrams and wireless communication devices for the duration of the operation. He did not elaborate.

He said he would report to al-Maliki on the progress of the operation on weekly basis, suggesting that the crackdown may last for weeks.

The security drive was announced by al-Maliki and Bush more than a month ago in a bid to stop the sectarian bloodletting that has left thousands dead and caused religiously mixed neighborhoods in Baghdad to change character as members of the minority sect fled after facing death threats or attacks.

Gambar said the security plan would include giving those who had occupied homes of displaced families a 15-day ultimatum to return the properties to the original owner or prove they had permission to be there.

Tuesday's suicide truck bombing, which also wounded 27 people, was the latest in a series of attacks since the announcement of the security crackdown aimed at stopping the sectarian violence that has killed hundreds since the start of the year.

Witnesses said the suicide bomber drove his explosives-laden truck into cars parked on a street as people were entering a Trade Ministry office that administers ration cards for the area.

The office and warehouses storing sugar and other rationed foodstuffs are located next to the private College of Economic Sciences, but it was closed for midterm so no students were among the casualties, police said.

Haider Hussein, a student who lives in the district, said the bomber was driving a small blue Kia truck.

"The explosion was so huge that it broke the windows of nearby offices and houses," he said, adding that 34 parked cars were burned. "I and some other people helped carry five wounded ministry guards to civilian cars that took them to the hospital."

A booby-trapped ambulance was discovered about 500 yards away, but police defused the explosives.

In other violence, the U.S. military said a soldier was killed Sunday in fighting in volatile Anbar province, west of Baghdad, raising to 42 the number of American deaths this month.

Police also found 28 bullet-riddled bodies showing signs of torture, most in Baghdad, apparent victims of so-called sectarian death squads.

Complete coverage is available in FOXNews.com's Iraq Center.