Today's car bomb outside a shrine in Najaf is now believed to have killed 82 people, including a leading Shi'ite Muslim.
More than 200 were injured, and 100 of those are said to be in a serious condition.
The explosion happened poutside the Tomb of Ali, one of Shia Islam's holiest shrines, as worshippers were leaving just after Friday prayers.
Ayatollah Mohammed Baqer al-Hakim was an Iraqi politician who had spent 20 years in exile in Iran before returning to Iraq earlier this year.
The US administrator in Iraq, Paul Bremer, condemned the attack on the Ayatollah al-Hakim, who had cooperated with the US occupation, allowing his followers to serve in US-sponsored national and regional governing bodies.
Ahmad Chalabi, leader of the Iraqi National Congress, blamed remnants of the Saddam Hussein regime and supporters of the al-Qaeda terror network for the attack.
Iran has declared three days of mourning for Ayatollah al-Hakim.
Blast at UK base in Basra
An explosion has taken place near a occupation force base in central Basra.
The incident happened about 6.30pm Irish time.
The explosion wrecked two cars about 100m from the main gate of the British army base but there were no injuries.
The base is on the banks of the Shatt al-Arab waterway, and is housed in a former palace of Saddam Hussein.
'It was a grenade, they threw it because the people sit on the bank and drink alcohol,' said one eyewitness. Another said the bomb was thrown from a passing car.
Another US soldier killed in Iraq
Earlier, another American soldier was killed and three others were wounded in Iraq.
The US military said their six-vehicle convoy was attacked near the town of Baquba, 40 miles north of Baghdad. They said the attackers used rocket-propelled grenades.
The area where the attack took place is regarded as the power base of Saddam Hussein.
