Suicide bombers have killed at least 120 people in two central Iraqi cities - in the deadliest day of attacks since elections last month.
Many pilgrims were killed in the attack on the shrine in Karbala
The first blast was near a major Shia shrine in Karbala, killing at least 60 people and injuring more than 100.
Soon afterwards, a blast at a police recruiting centre in Ramadi killed around 60 and injured some 60 others.
In Baghdad, a roadside bomb killed five US soldiers. The capital was also hit by three car bombs.
On Wednesday more than 50 people died in attacks across Iraq.
Iraqi President Jalal Talabani said those who thought the attacks would drive a wedge between Iraq's religious groups and destabilise the political process were wrong.
"These groups of dark terror will not succeed through these cowardly acts in dissuading Iraqis in their bid to form a government of national unity," he said.
Discussions are going on between Shia, Sunni and Kurdish parties to establish a coalition government once the final results from December's parliamentary elections are released.
The Ramadi explosion occurred at 1055 (0755 GMT) when the bomber blew himself up among a crowd of about 1,000 applicants queuing in a police recruitment drive.
BLOODIEST VIOLENCE IN IRAQ
5 Jan 2006 - 110 dead
Suicide bombers hit Karbala shrine and police recruiting station in Ramadi
18 Nov 2005 - 80 dead
Multiple bombings in Baghdad and two Khanaqin mosques
14 Sept 2005 - 182 dead
Suicide car bomber targets Baghdad labourers in worst of a series of bombs
16 Aug 2005 - 90 dead
Suicide bomber detonates fuel tanker in Musayyib
28 Feb 2005 - 114 dead
Suicide car bomb hits government jobseekers in Hilla
24 June 2004 - 100 dead
Co-ordinated blasts in Mosul and four other cities
2 March 2004 - 140 dead
Suicide bombers attack Shia festival-goers in Karbala and Baghdad
1 Feb 2004 - 105 dead
Twin attacks on Kurdish parties' offices in Irbil
28 Aug 2003 - 85 dead
Car bomb at Najaf shrine kills Shia cleric Muhammad Baqr Hakim and many others
US military spokesman Capt Jeffrey Pool said surviving recruits later got back in line to continue the screening process.
Iraqi police and officials are regularly targeted by insurgents, and the city has been a rebel stronghold for many months.
In Karbala, the bomber blew himself up at about 1000 (0700 GMT) in a crowded pedestrian area between the Imam Hussein shrine and the nearby shrine to Imam Abbas.
The bomber's suicide vest had been laced with ball bearings and grenades, police said.
The area is popular with pilgrims and foreigners may be among the casualties.
Mohammed Sahib, a pilgrim who sustained a head injury, condemned the attack.
"I never thought that such a crime could happen near this holy site," he told the Associated Press.
"The terrorists spare no place from their ugly deeds. This is a criminal act against faithful pilgrims. The terrorists are targeting the Shias."
Iraqi television showed body parts and torn clothing in pools of blood.
Survivors were being evacuated in ambulances, cars and vans.
Police spokesman Raman Ashawi said the final number of dead could be much higher.
A tribal leader in the area told the BBC the city had been sealed off to traffic after reports that there may also be a car bomb in the vicinity.
Thursday's attack was the bloodiest in Karbala since March 2004, when 85 people were killed and 230 were injured as co-ordinated bombings near the main mosque targeted Shias celebrating the festival of Ashura.