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Iraqi interim Prime Minister Ayad Allawi (search) 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 (search), 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 10 explosions rocked central Baghdad, apparently targeting the fortified Green Zone (search) enclave housing the U.S. Embassy and Iraqi interim government buildings. Their cause was not immediately known.

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. servicemembers 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.

Iraqi officials earlier said the amnesty might extend to those who killed U.S. and other coalition troops. U.S. officials said an early draft was ambiguous on that issue, but later drafts ruled it out.

The amnesty was rejected immediately by militant Shiite cleric Muqtada al-Sadr, whose militia has been fighting coalition forces in the Shiite holy city of Najaf and elsewhere since Thursday.

"This is a trivial and insignificant statement," said al-Sadr aide Ahmed al-Shaibany. "Amnesties are for criminals, but resistance is legitimate and does not need an amnesty."

Those eligible would need to turn themselves in during the next 30 days and provide information on their crimes and other crimes they know about, Allawi said. The amnesty period could be extended.

"This order has been established to allow our citizens to rejoin civil society and participate in the reconstruction of their country and the improvement of their lives, instead of wasting their lives pointlessly toward a lost cause," he said.

Scattered fighting continued Saturday in Shiite areas of Iraq, as Shiite leaders appealed for a cease-fire to end the violence, which threatens to re-ignite a two-month Shiite insurrection that broke out in April.

Al-Sadr aides met in Baghdad with Iraqi dignitaries and U.N. official Jamal Benomar.

"We called for a more effective U.N. role, the end of military actions, respecting the truce and a political solution for this crisis," said Ali al-Yassiry, an al-Sadr aide.

The Shiite Political Council, an umbrella group representing 38 Shiite movements, said it would boycott a national conference this month if violence continued.

Iran's supreme leader Ayatollah Ali Khamenei blamed the United States for the fighting.

"The United States has reached a dead end in Iraq, like a trapped wolf, and it is trying to frighten people by roaring and clawing," state-run Tehran radio quoted him as saying.

Explosions and gunfire continued Saturday in Najaf but most streets appeared deserted. U.S. warplanes flew overhead and American armored vehicles and Humvees blocked main roads into the city.

Allawi said more than 1,200 people had been arrested during the clashes, including followers of Saddam's regime and common criminals released by Saddam.

"The Iraqi police, National Guard and the army will escalate their operations against the outlaw people. This should be clear," he said.

The U.S. military said it secured the cemetery where insurgents were hiding. Marines found weapons caches, including bomb-making materials, rocket-propelled grenades, assault rifles and ammunition.

However, the militants appeared to control Najaf's old city, with vehicles and gunmen spread throughout the streets.

Militia fighters also insisted they controlled the southern city of Amarah. Associated Press Television News footage showed them directing traffic and driving police cars in the city.

The insurgents have overrun small police stations in town and looted them, "but they haven't overtaken the whole town," said British military spokesman Maj. Ian Clooney.

In the southern city of Basra, gunmen attacked the governor's office at dawn with rifles and mortar rounds. Police returned fire, repelling the attack and killing one gunman, police Capt. Mustaq Talib said.

In other violence, a militant group said Saturday it had taken a Turkish truck driver hostage and threatened to behead him within 48 hours if his company did not leave Iraq. His company quickly announced it would withdraw.

Militants have taken scores of foreigners hostage in recent months, trying to drive coalition troops out of Iraq and hamper reconstruction efforts.