Suspected al-Qaeda insurgents on Wednesday destroyed the two minarets of the Askariya Shiite shrine in Samarra, authorities reported, in a repeat of a 2006 bombing that shattered its famous Golden Dome and unleashed a wave of retaliatory sectarian violence that still bloodies Iraq. Police said the attack at around 9 am involved explosives and brought down the two minarets, which had flanked the dome’s ruins. No casualties were reported.The attack, blamed on Sunni Muslim extremists, immediately stirred fears of a new explosion of Sunni-Shiite bloodshed. State television said Prime Minister Nouri al-Maliki quickly imposed an indefinite curfew on vehicle traffic and large gatherings in Baghdad, as of 3 pm on Wednesday.The Iraqi leader also met with the US commander in Iraq to ask that American reinforcements be sent into Samarra to help head off new violence in the flashpoint city 60 miles north of Baghdad, al-Maliki’s office said.The powerful blasts shook the town, sending a cloud of dust billowing into the air, said Imad Nagi, a storeowner 100 yards from the shrine. “After the dust settled, I couldn’t see the minarets any more. So, I closed the shop quickly and went home.”It wasn’t immediately clear how the attackers evaded the shrine’s guard force, which had been strengthened after the 2006 bombing.In the aftermath of Wednesday’s explosions, police in the shrine area began firing into the air to keep people away, witnesses said, and Iraqi army and police reinforcements poured in. A national police force under command of a major general was ordered to move immediately to Samarra, said an Interior Ministry official.Radical Shiite cleric Muqtada al-Sadr called for a three-day mourning period to mark the minarets’ destruction and criticised the government for not doing enough to protect the site.Al-Sadr also called for peaceful demonstrations following the blasts “to show that the only enemy of Iraq is the occupation and that’s why everyone must demand its departure or scheduling its presence.”Al-Sadr uses the word “occupation” to refer to the presence of US troops in Iraq.Al-Maliki, in his meeting with US commander Gen David Petraeus and US Ambassador Ryan Crocker, asked that US troops in Baghdad be put on a higher alert to head off any upsurge in Sunni-Shiite bloodshed, said an al-Maliki aide, speaking on condition of anonymity.The aide and other officials spoke on condition of anonymity.The US command had no immediate comment on such military moves.The official close to al-Maliki, citing intelligence reports, said the attack was likely the work of al-Qaeda, whose militants have recently moved into Samarra from surrounding areas.After Wednesday’s bombing, al-Maliki, a Shiite, went into urgent talks with Saleh al-Haidari, chairman of the Shiite Waqf, the government agency that looks after Shiite mosques and religious schools, according to officials in al-Maliki’s office.