More than 130 Iraqis - most of them Sunni Arabs - have been killed in two days of surging sectarian violence following Wednesday's bombing of one of the holiest sites in Shi'ite Islam.
Dozens of Sunni mosques have been attacked despite calls from Iraqi political and religious leaders who fear civil war.
Police found dozens of bodies in and around Baghdad overnight after attackers blew up the Askariya mosque in Samarra. Outside Baghdad, authorities found the bodies of 47 people shot to death.
Near Samarra, gunmen killed three journalists working for Dubai-based Al-Arabiya television network. Press rights group Reporters Without Borders condemned the killing of the three, who had been reporting from the scene of the mosque attack.
In the southern city of Basra, gunmen dressed in police uniforms raided a prison and killed 11 Sunni detainees, including several foreign militants.
A major Sunni political alliance, the Iraqi Accordance Front, says it will not attend a multi-party meeting President Jalal Talabani has called to discuss the situation, and will boycott talks on forming the next government.
And in northern Iraq, two roadside bombs killed seven U.S. soldiers Wednesday.
As sectarian violence flared, authorities placed security forces on high alert and extended curfew hours in Baghdad and several other cities.
The Askariya shrine draws pilgrims from around the world. It contains the tombs of the 10th and 11th Shi'ite imams, Ali al-Hadi and his son, Hassan al-Askari, who died in 874. The shrine was built at the site where the 12th Shi'ite imam, Mohammed al-Mahdi, disappeared. He is called the hidden imam and is the son and grandson of the two imams buried at Askariya.