Iraqi Prime Minister Nouri al-Maliki has moved quickly to prevent any escalation of sectarian violence following the bombing of a Shi'ite shrine north of Baghdad. An attack on the same shrine last year triggered the current cycle of Sunni-Shi'ite violence that has engulfed parts of the country. From northern Iraq, VOA's Margaret Besheer has more.

Early Wednesday, at least two explosions at the Askariya shrine collapsed the mosque's two minarets within minutes of each other.

An attack last February on the same shrine, in the city of Samarra some 95 kilometers north of Baghdad, damaged its famed golden dome and propelled the country into its current cycle of sectarian killings.

There were no casualties in Wednesday's blast, but the government acted quickly to prevent possible reprisal attacks. Prime Minister Nouri al-Maliki, a Shi'ite, addressed the nation calling for restraint and said security has been tightened at all of Iraq's religious sites.

Mr. Maliki called on all Iraqis - ordinary citizens, leaders and religious figures - to talk to the people and to urge them to show restraint and to be vigilant so those that are trying to harm the country will not succeed.

The prime minister announced the establishment of a commission of inquiry to investigate the attack. The shrine was heavily guarded by the country's Shi'ite-dominated police forces, raising questions as to how the attackers circumvented them.

Mr. Maliki said those guarding al-Askariya have been arrested and are being questioned. He said the government's action would be severe against anyone involved in this crime.

In Samarra, a curfew was imposed indefinitely, while in the capital, vehicle traffic was banned after 3 o'clock local time. But despite the crackdown, a Sunni Muslim mosque in northern Baghdad was set on fire.

Fears are high that the bombing might further inflame the sectarian violence that swept Baghdad and other parts of Iraq following the destruction of the shrine's golden dome on February 22 last year. Those sectarian attacks continue, despite Iraqi and U.S. efforts to increase troops in the worst affected areas.

Mr. Maliki blamed the attack on Saddamists, extremists and al-Qaida.

He said all those who stand with the Saddamists and al-Qaida should pay the price and Iraqis should stand hand-in-hand with the security forces.

The American ambassador to Iraq, Ryan Crocker, and the commander of forces here, General David Petraeus, issued a joint statement condemning the attack calling it "a deliberate attempt by al-Qaida to sow dissent and inflame sectarian strife."

Anti-American Shi'ite cleric Moqtada al-Sadr also condemned the blast and urged restraint. In a statement, he called for three days of mourning and peaceful protests and for the shrine to be rebuilt.

The Askariya shrine is important to Shi'ite Muslims because it contains the tombs of two ninth century Shi'ite imams. It is also the place where Shi'ites believe their last imam, Mohammed al-Mahdi, disappeared.

In the immediate aftermath of last year's attack, Shi'ites struck against Sunni Muslim mosques and worshippers. In Baghdad alone, angry crowds attacked at least 27 mosques and killed dozens of people. The United Nations says sectarian inspired violence in 2006 killed nearly 35,000 Iraqis.