A suicide bomber killed at least six worshippers at a mosque in central Baghdad on Monday, blowing himself up during morning prayers.
The attacker tried to enter the mosque around lunchtime but detonated his device when guards tried to search him, police said, adding that 32 other people had been injured.
The explosion took place in the Shorja market area, where a truck bomb killed 137 people last month.
Iraqi authorities have imposed strict security in the area to prevent car bombings as part of a wider security crackdown in the capital.
The attack happened a day before the fourth anniversary of the first air strikes heralding the United States-led invasion of Iraq.
Since then, the United States has suffered 3 217 combat fatalities in Iraq, among them seven soldiers killed during the weekend, four by a roadside bomb in western Baghdad.
Despite the month-long security crackdown in the capital, six people were killed and 30 injured by a car bomb blast in a Shia suburb on Sunday. In all, 24 corpses were found in different parts of the city.
Near Ramadi, capital of Sunni Anbar province where al-Qaeda has a strong presence, police found the decapitated bodies of nine policemen with their hands bound and bearing signs of torture.
General David Petraeus, the new commander of US forces, spoke of ”encouraging signs” in Baghdad but told the BBC he did not want to get ”overly optimistic on the basis of several weeks of a reduced sectarian murder rate”. The US troop ”surge” has allowed hundreds of Iraqi families to return to homes abandoned in the face of sectarian attacks. But Petraeus said the situation would be clearer by June, when all extra forces were in position.
Another US spokesperson blamed al-Qaeda for the chlorine bomb attacks in Anbar on Friday and said tighter Iraqi security had prevented more casualties.
Three suicide bombers driving trucks rigged with tanks of the toxic gas killed two policemen and left 350 Iraqi civilians injured.
In the US, demonstrators took to the streets to observe the fourth anniversary of the war. In Washington, several thousand marched to the Pentagon, in an echo of the October 1967 protests against the Vietnam war. ”They take their death and destruction and export it around the world,” said the anti-war activist Cindy Sheehan, who lost her son in Iraq. – Guardian Unlimited Â