BAGHDAD A suspected al Qaeda bomber killed 78 people when he rammed a truck into a Shi'ite mosque in Baghdad on Tuesday, just hours after 10,000 U.S. troops began an offensive against the Sunni Islamist group north of the capital.
The offensive around the city of Baquba in Diyala province is partly aimed at al Qaeda car bomb networks that cause carnage in Baghdad. It is one of the biggest military operations since the invasion of Iraq in 2003.
One witness said the bomber drove his truck into the Khilani mosque in Baghdad, destroying one wall and wrecking part of the building's interior. The mosque's signature turquoise dome appeared to have suffered little damage.
Shi'ite Prime Minister Nuri al-Maliki blamed the attacks on "Saddamists and Takfiris", a term commonly used by Iraqi officials to describe al Qaeda. "It shows (their) determination to ignite sectarian violence," Maliki said in a statement.
Police said 78 people had been killed, including at least nine women, and 224 others were wounded. Rescuers dragged bodies from the mosque while the charred remains of others could be seen in burned out minibuses around a nearby traffic circle.
It was the second worst bombing in Baghdad since U.S. and Iraqi forces launched a crackdown in February in the capital aimed at halting Iraq's spiral into all-out sectarian civil war. A car bomb on April 18 killed 140 near a Baghdad market.
"Iraqis in this country are being killed every day. No one takes care of them," shouted one old man at the scene.
Iraqi military spokesman Brigadier-General Qassim Moussawi said the truck had been loaded with gas canisters and half a metric ton of explosives.
The explosion followed a relatively quiet period in Baghdad after a four-day curfew was imposed last week in the wake of an attack on a revered Shi'ite shrine in the city of Samarra that was also blamed on al Qaeda.
Militants also fired a barrage of mortar bombs at Baghdad's Green Zone in one of the heaviest attacks in weeks on the compound that houses the U.S. embassy and government offices.
The U.S. embassy said no U.S. citizens were killed or wounded in the attack just before sundown. There was no other information about possible casualties.
The U.S. military said 22 militants were killed in the early hours of the offensive against al Qaeda around Baquba. Diyala province is a stronghold of the Sunni Islamist group but it also has significant Shi'ite and Kurdish populations.
"The end state is to destroy the al Qaeda influences in this province and eliminate their threat against the people," Brigadier-General Mick Bednarek, deputy commanding general, operations, 25th Infantry Division, said in a statement.
"That is the number one, bottom-line, up-front, in-your-face, task and purpose."
The statement said about 10,000 soldiers, backed by attack helicopters, close air support and armored fighting vehicles were taking part in Operation Arrowhead Ripper.
It did not say how long the offensive would last. But it coincides with smaller operations launched in recent days against al Qaeda targets around Baghdad.
"It's certainly one of the largest since the end of ground operations in 2003," U.S. military spokesman Lieutenant-Colonel Christopher Garver told Reuters when asked to describe the significance of the operation.
Residents in Baquba, capital of Diyala, said heavy and continual explosions echoed around the city since before dawn. Baquba, 65 km (40 miles) north of Baghdad, was under total curfew, they added.
The operation comes just days after the U.S. military said it had completed its troop build-up in Iraq to 160,000 soldiers.
South of the capital, gunmen loyal to Shi'ite cleric Moqtada al-Sadr battled police linked to a rival Shi'ite faction for a second day in the city of Nassiriya. Hospital officials said 35 people had been killed over the past two days.
The fighting underscored frictions between Sadr's political movement and the Supreme Iraqi Islamic Council (SIIC), which have raised fears of a battle for control of Iraq's more stable Shi'ite southern regions.
(Additional reporting by Paul Tait, Alister Bull, Ross Colvin, Waleed Ibrahim and Aseel Kami)