Today’s attack on the al-Askariya Shia shrine in Samarra was designed to stoke further the sectarian tensions that have killed tens of thousands of Iraqis since the holy site, north of Baghdad, was first bombed 15 months ago.

Religious and political leaders called for calm after the shrine’s two minarets were destroyed, but people in the Iraqi capital were preparing themselves for another wave of violence.

“This attack happened in a bid to divide the Iraqi people,” said Samia Khasra, an Iraqi MP. “Religious sites are the best place to hit us. When they bombed the shrine the first time they saw the response and they know that it is a good way to try and divide us,” she told The Times.

The Government, which blamed al-Qaeda for the bombings, imposed a curfew in Baghdad to limit the movement of militias on the streets and hopefully stem any violent repercussions.

Iraq's revered Shia cleric Grand Ayatollah Ali al-Sistani and his more radical counterpart, Hojatoleslam Moqtada al-Sadr, also appealed for calm.

People living in mixed Sunni-Shia neighbourhoods in Baghdad, where sectarian killing has been most prevalent, however, were bracing themselves for the worst. “We are preparing for any attack by the Mahdi Army,” said Shiras Assem, a 34-year-old shop keeper living in Saideyah, west Baghdad, referring to the group loyal to Hojatoleslam al-Sadr.

“We closed the street and we expect to be attacked,” he said. “Maybe they will hit the local Sunni mosque. We have set up a night watch until the morning. We will not sleep tonight.”

Nearby, Marwan Faleh, a 38-year-old broker, was also nervous. “We have gathered together the young me in our street, each one has a weapon. We told them to be ready if anyone attacks us we will all open fire,” Mr Faleh said.

“We expect an attack during the curfew because we don’t trust the checkpoint at the end of our road. I plan to stay at home over the next few days because I believe more people will be killed.”

Violence had already erupted at a Sunni mosque in Ghazaliyah, a mixed Sunni-Shia neighbourhood in north Baghdad, said one resident, who asked to remain anonymous.

Mortars were aimed at the El-Muhajareen Mosque followed by clashes between gunmen and the guards inside the mosque. After 45 minutes, the Iraqi Army and National Guard arrived at the scene to secure the area, the resident said.

Dr Foad Kazem al-Moqdadi, a Sunni academic who had been a participating in a three-day conference on religious reconciliation that ended today, said the Samarra attack was carried out by “terrorists who want to start a fight between Sunni and Shia”.

He blamed the Government and the Iraqi security forces for failing to stop the explosions, particularly because the shrine’s defences were strengthened after its golden dome was bombed in February last year. That attack ignited horrific clashes between Sunni and Shia groups, escalating the insecurity that has plagued Iraq in the aftermath of the US-led invasion.

“We were getting very close to stopping the violence sparked by the first bombing, and now it happens again,” said Dr al-Moqdadi.

On the positive side, he said Iraqis knew the perpetrators were solely intent on stoking sectarian warfare and they would therefore be more willing to resist rising to the bait. “We are very strong now more than the last time,” he said. “I have heard that militant groups have started to fight some Sunni groups in the street, but we will try to stop this sort of thing happening."

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