Insurgents killed at least 23 people and wounded around 90 in a series of suicide attacks and bombings in Shi'ite Muslim districts of Baghdad today, the holiest day of the Shi'ite religious calendar.
Iraq's security forces had been braced for attacks in the southern holy city of Kerbala, where more than 170 pilgrims were killed during the Shi'ite ritual of Ashura last year.
But guerrillas targeted the capital, which has borne the brunt of violence since last month's elections.
In the worst attack, a man wearing a vest laden with explosives boarded a bus in the Shi'ite Khadamiya district and blew himself up, according to witnesses and the US military.
Police said 17 people were killed and 41 wounded in the blast, close to a barrier protecting a Shi'ite mosque.
In a separate attack in the same area, a suicide bomber blew himself up after an exchange of fire with security forces. One US soldier was killed.
Earlier, a suicide bomber on a motorbike attacked a group of people attending the funeral of a woman killed in one of Friday's bombings. Four mourners were killed and 39 wounded, hospital officials said.
While Baghdad was rocked by the blasts, Shi'ites in Kerbala were able to observe Ashura in relative peace.
Officials said several hundred thousand pilgrims marched through the city's streets, chanting, beating their breasts and crying "Hussein" in honour of Imam Hussein, a grandson of the Prophet Mohammad, who died in a battle in 680 A.D.
Some cut themselves with knives in a symbolic act of atonement for Hussein's death.