Sectarian tensions, already at a peak, were further inflamed yesterday in Iraq when bombers blew up a car in the Shiite holy city of Karbala, killing at least five and wounding 25.
The fresh attack came after more than 140 people were killed nationwide in a surge of sectarian blood-letting triggered by the bombing Wednesday of one of the holiest Shiite shrines in Samarra, north of Baghdad.
In another attempt to inflame the situation, bombers yesterday blew up a well-known Shiite tomb in Taz Khurmatu, in northern Iraq, police said.
The Karbala bombing targeted a busy shopping street in the west of the city as a police patrol passed by.
Three policemen were among those killed, said police who later announced that a suspect had been arrested.
The bombing posed a new challenge to authorities as they try to calm sectarian tensions.
In other violence, 12 farm laborers were shot to death in an orchard yesterday morning in Diyala province, northeast of Baghdad.
They included both Shiites and Sunnis, a relative of the victims said.
Police said that seven more bodies were found in Baghdad, four in the capital's Sunni Azamiyah district and three in the southeastern Kamaliyah district.
Two policemen were killed and five wounded when a bomb targeted the funeral procession west of Baghdad of a journalist killed on Wednesday in Samarra where she had gone to report on the shrine bombing, police said.
The procession had earlier also been shot at with one more policeman killed.
The government slapped a 20-hour curfew both Friday and yesterday on Baghdad and three more central provinces in a bid to keep demonstrations off the street. Petrol stations were closed.
Iraqi Prime Minister Ibrahim Jaafari also announced a clampdown on the carrying of weapons in public without a permit and a ban on demonstrations by armed men.
Army and police checkpoints sprung up mushroom-like in the streets of Baghdad yesterday forcing people to stay indoors.
The rising sectarian violence threatens to derail talks on setting up a government of national unity -- a move considered vital by the US in removing the sting from the insurgency raging in Sunni areas and paving the way for the withdrawal of its troops.
US President George W. Bush acknowledged that the situation is serious.
"We can expect the coming days will be intense," he said in Washington on Friday.
"Iraq remains a serious situation. But I'm optimistic," Bush said.
In Shiite areas of central and southern Iraq, religious leaders appealed for restraint in their sermons on the Muslim day of rest on Friday.
"We must proclaim our commitment to live side by side, peacefully, and reject all violence to preserve the unity of the people," Abdel Mehdi al-Karbalai, a representative of the Shiite spiritual leader Grand Ayatollah Ali al-Sistani, said in Karbala.
Iraq's Construction Minister Jassem Mohammed Jaafar who toured the devastated Samarra shrine on Thursday gave the first assessment of the attack, saying he believed that it was the work of specialists.
"Holes were dug into the mausoleum's four main pillars and packed with explosives," he told state television.
"Then the charges were connected together and linked to another charge placed just under the dome. The wires were then linked to a detonator which was triggered at a distance," the minister added.