Baghdad, Iraq ? Iraqi interim Prime Minister Iyad Allawi signed an amnesty Saturday intended to persuade militants fighting a 15-month-old insurgency to put down their weapons and join government efforts to rebuild the country.

But the law pardons only minor criminals, not killers or terrorists, and appeared unlikely to dampen the violence, as some insurgent leaders called it “insignificant.”

Meanwhile, sporadic explosions and gunfire echoed through Najaf, south of the capital, as Shiite leaders appealed for a renewed cease-fire to end two days of bloody battles between insurgents and Iraqi and U.S. forces in several Shiite communities.

On Saturday night, at least 12 explosions rocked central Baghdad, apparently targeting the fortified Green Zone enclave housing the U.S. Embassy and Iraqi interim government buildings. The military said some of the explosions appeared to be mortars.

The Najaf fighting has threatened to revive a Shiite insurrection that broke out in April and was calmed only in a series of truces in June.

Five U.S. service members have been killed in Najaf, including two Marines who died Friday, the military announced. The military says hundreds of militants have been killed, though the militiamen put the number far lower.

Also Friday, an insurgent fired a rocket-propelled grenade at a U.S. vehicle in Baghdad, killing one soldier. At least 925 U.S. service members have died since the beginning of military operations in Iraq in March 2003.

The Iraqi government also ordered the offices of the pan-Arab television station Al-Jazeera closed for 30 days, accusing it of inciting violence.

“They have been showing a lot of crimes and criminals on TV, and they (send) a bad picture about Iraq and about Iraqis and encourage criminals to increase their activities,” Iraqi Interior Minister Falah al-Naqib said.

An Al-Jazeera spokesman called the closure “unwise” and said it restrained freedom of the press.

The long-delayed amnesty, coupled with a tough emergency law passed last month, was supposed to help end the violence by coaxing nationalist guerrillas to the government’s side.

The amnesty applies to minor crimes — such as weapons possession, hiding intelligence about terror attacks or harboring terrorists — and appears intended to persuade people with information on attacks to share it with police.

The amnesty forgives those who committed minor crimes between May 1, 2003, just after Saddam Hussein’s regime fell, and Saturday, Allawi said.

“This amnesty is not for people … who have killed. Those people will be brought to justice, starting from Zarqawi down to the person in the street,” Allawi said, referring to Jordanian militant Abu Musab al-Zarqawi, whose followers have claimed responsibility for deadly suicide bombings.

Rape, kidnapping, looting and terror attacks also are excluded.