Bomb blasts rocked four Christian churches in Baghdad and two in the northern Iraqi city of Mosul today, killing at least 15 people.
At least 12 of those were killed in just one of the attacks on churches in Baghdad a witness said.
According to the witness a car raced into the parking lot of the Chaldean church in the southern Baghdad neighbourhood of Doura and exploded as people were leaving a service.
He said he saw at least 12 people dead and body parts scattered across the area.
Christians total about 800,000 or three per cent of Iraq's 24 million population and mainly live in Baghdad. Assyrian Christians, also known as Chaldeans, comprise the biggest group.
Christians were free to worship under Saddam Hussein who, despite his persecution of majority Shi'ites, officially preached religious tolerance.
It is the latest in a series of bloody incidents in Iraq today. A suicide car bomber blew up his vehicle outside a police station in the northern city of Mosul , killing at least five people and wounding 50, police and doctors said.
Witnesses said the Toyota Landcruiser raced towards a police checkpoint as guards screamed at the driver to stop. When he did not, they opened fire, killing him, but the car ploughed on and detonated about 20 metres (60 feet) from the police station.
A police lieutenant said the five killed were police officers and the wounded were a mix of civilians and police. Doctors said they expected the death toll to rise and said many of the 50 wounded were badly hurt.
The bombing came four days after a similar attack outside a police recruiting centre in the town of Baquba, north of Baghdad, killed 70 people. Police are frequently targeted by militants who regarded them as collaborators with US forces.
Today's attack followed another night of clashes between US forces and guerrillas in the rebellious city of Falluja, west of Baghdad, in which at least 10 Iraqis died and 35 were wounded, a doctor at the main hospital said.
There has been heavy fighting in and around Falluja in recent days, with US marines backed by tanks and aircraft targeting particularly restive neighbourhoods.
The marines tried to take over the city in April but withdrew after several weeks of bloody fighting. An Iraqi force is now responsible for Falluja's security, but US officials say it has become a safe haven for guerrillas and kidnappers.
In recent days, the US military has carried out air strikes in Falluja, targeting houses thought to have been used by Jordanian militant Abu Musab al-Zarqawi, who Washington believes is allied to al-Qaeda.
Yesterday, militants purportedly led by Zarqawi said they had kidnapped two truck drivers and would behead them in 48 hours unless their Turkish company quit the country.
The kidnapping was the latest in a growing wave of hostage-taking that has hit Iraq since April.
Al Jazeera television screened a video tape showing the two drivers in front of a group of masked gunmen and said the militants had vowed to behead the hostages unless their firm stopped supplying the US military in Iraq and quit the country completely.