At least eight people were killed and 22 wounded by a car bomb in the southern Doura district of the Iraqi capital, Baghdad, police said.
The Doura district has frequently been the target of attacks
The bomb exploded about 10m from a Sunni mosque at 1300 (1000 GMT). Most of the victims were worshippers attending Friday prayers.
An imam from a Sunni mosque in the west of Baghdad was also abducted by gunmen.
A roadside bomb also killed two US Marines near the city of Falluja, the US military has said.
The Marines died on Thursday when their patrol was targeted near the city, 65 kilometres (40 miles) west of Baghdad.
Nine US troops have died in Anbar Province in the past week.
The deaths take the number of US soldiers killed to more than 2,260 since the Iraq war began in March 2003.
Falluja is tightly controlled by the US military following a US-led offensive in November 2004.
The operation was meant to end insurgent activity in the city.
In Doura, the bomb caused chaos, a man who was praying at the time of the blast said.
RISE IN INSURGENT ATTACKS
Total attacks: 26496
Improvised bombs: 5607
Car bombings: 420
Suicide car bombings: 133
Suicide bombers wearing explosive vests: 7
Total attacks: 34131
Improvised bombs: 10593
Car bombings: 873
Suicide car bombings: 411
Suicide bombers wearing explosive vests: 67
"Some worshippers were leaving and others were praying inside when the explosion blasted glass all over us and smoke filled the mosque," Ahmed Hasan told the Associated Press.
"Outside we were shocked to see so many wounded people and cars on fire."
The attack on the mosque came as a Sunni cleric was abducted by gunmen from his home in the capital's Babil district.
Sheikh Adil Khalil Dawoud's relatives said the gunmen were wearing Interior Ministry police uniforms.
Meanwhile, figures released by multi-national forces in Iraq show a sharp rise in attacks on their troops in 2005 from 2004.
Attacks using improvised explosive devises rose from 5,607 in 2004 to 10,593 in 2005.
Suicide attacks using cars rose from 133 in 2004 to 411 in 2005.
Attacks by militants wearing vests carrying explosives rose from 7 in 2004 to 67 in 2005.
US officials have said that the figures should not be seen as evidence that insurgents are gaining ground because the effectiveness of their attacks declined.