At least 62 people have been killed in three co-ordinated car bombs in a city near Baghdad, Iraqi police say.
The near-simultaneous blasts in Balad, 50 miles (80km) north of the capital, injured at least another 68.
The suicide bombs went off in a busy vegetable market, by a bank and by a police station in the mainly Shia city, Iraqi police said.
The attack came as the commander of US forces in Iraq said the next 75 days were crucial to Iraq's future.
'Enemy of peace'
Testifying before a congressional committee in Washington, Gen George Casey said if the new Iraqi constitution was rejected in a referendum in two weeks' time, the situation could deteriorate.
Gen Casey said he would not speculate on any withdrawal of US troops from Iraq until after that period. A reduction in coalition forces remained a possibility for 2006, he said.
He admitted that the number of Iraqi army battalions capable of operating without US support had fallen since June from three to one.
His colleague, Gen John Abizaid, told a congressional hearing that al-Qaeda was the main enemy of peace and stability in the Middle East and the threat it posed should not be underestimated.
US soldiers killed
In Iraq, the US military said five US soldiers had died in a roadside bombing in the western town of Ramadi.
The bomb exploded as they conducted combat operations on Wednesday, a statement by the Marines said.
The Sunni town of Ramadi is a stronghold of Iraq's anti-US insurgents, who launch regular attacks against Iraqi and American troops.
Reports say 13 US service personnel have been killed in violence in Iraq in the past five days.
Almost 2,000 American military personnel have died in Iraq since the US-led invasion two-and-a-half years ago.