At least 20 people were killed and dozens more were wounded when snipers opened fire from rooftops and a cemetery in a series of attacks on a Shiite religious procession in Baghdad.
The "terrorist assaults" took place when the pilgrims were walking through Sunni areas on their way to the shrine of Imam Moussa Kadhim, one of 12 Shiite saints, said Health Ministry spokesman Qassim Allawi.
The violence defied a weekend driving ban to prevent car bombs amid a cycle of tit-for-tat attacks by Shiites and Sunnis in Iraq since the February 22 bombing of a Shiite mosque in Samarra. The sectarian warfare, along with the deadly Sunni Arab insurgency, has become the biggest challenge for the US-backed national unity government. About 12,000 extra US and Iraqi troops have been deployed in recent weeks as part of a security crackdown in the capital as many fear the bloodshed, which is claiming about 100 lives a day, could lead to an all-out civil war.
The ceremonies at the shrine in the northern Baghdad neighbourhood of Kazimiyah continued despite the attacks, which Allawi said occurred in three or four neighbourhoods at least a mile away.
Shiite pilgrims, wearing white shrouds to symbolise their willingness to die for Islam, chanted "God bless [Prophet] Muhammad and his descendants," as they converged on the area.
Shiites believe that Kadhim, who died in 799, was poisoned in prison by a Sunni caliph. He is buried inside the golden-domed shrine along with his grandson.
Military spokesman Col Saddoun Abu al-Ula said 20 pilgrims were killed and 304 injured. Four militants, including two snipers, were killed.
"I was walking and someone got shot in front of me. It was a clear sniper attack," said Mohammed Jassim, 32.
The Iraqi Islamic Party, the main Sunni party, accused government forces and armed militias, a reference to Shiites, of killing "peaceful people".
"We call on the govern-ment to adopt a strict stand against anybody who tries to create chaos and disord er," said a party statement.
Fadhil al-Sharaa, an aide to Shiite Prime Minister Nouri Maliki, claimed some o ne million people attended the procession.