Some 3,000 Christians have fled the city over the past week alone in a "major displacement," said Duraid Mohammed Kashmoula, the governor of northern Iraq's Ninevah province. He said most have left for churches, monasteries and the homes of relatives in nearby Christian villages and towns.

"The Christians were subjected to abduction attempts and paid ransom, but now they are subjected to a killing campaign," Kashmoula said, adding he believed "al-Qaida" elements were to blame and called for a renewed drive to root them out.

Political and religious leaders interviewed said the change in tactics may reflect a desire on the part of extremists to forcibly evict all Christians from Iraq's third largest city.

Earlier this week, Chaldean Archbishop Louis Sako said he was worried about what he termed a "campaign of killings and deportations against the Christian citizens in Mosul."

Mosul police have reported finding the bullet-riddled bodies of seven Christians in separate attacks so far this month, the latest a day laborer found on Wednesday. On Saturday, militants blew up three abandoned Christian homes in eastern Mosul, police said.

Father Bolis Jacob of Mosul's Mar Afram Church said he was at a loss to understand the violence. "We respect the Islamic religion and the Muslim clerics," he said. "We don't know under what religion's pretexts these terrorists work."

The violence in Mosul occurs despite U.S.-Iraqi operations launched over the summer aimed at routing al-Qaida in Iraq and other insurgents from remaining strongholds north of the capital.

The killings come as Christian leaders are lobbying parliament to pass a law setting aside a number of seats for minorities, such as Christians, in upcoming provincial elections, fearing they could be further marginalized in the predominantly Muslim country.

Iraq's Christian community has been estimated at 3 percent of Iraq's 26 million people, or about 800,000, and has a significant presence in the northern Ninevah province.

In Mosul, where Christians have lived for some 1,800 years, a number of centuries-old churches still stand.

Joseph Jacob, a professor at Mosul University, said there were nearly 20,000 Christians in the city before the 2003 U.S. invasion. But over half have since left for neighboring towns, or new countries, he said.

Islamic extremists have frequently targeted Christians since the invasion, forcing tens of thousands to flee Iraq. Attacks had tapered off amid a drastic decline in overall violence nationwide, but that appears to be changing with the deaths this month.

On Saturday, Bashir Azoz, a 45-year-old carpenter, said he was forced to flee his home in the city's eastern Noor area after gunmen warned a neighbor the day before to leave or face death.

"Where is the government and its security forces as these crimes take place every day?" asked Azoz, who is now staying with his wife and three children in a monastery in the Christian-majority town of Qarqoush, east of Mosul.

Separately on Saturday, a U.S. soldier died when a bomb exploded near his vehicle outside Amarah, southeast of Baghdad. The U.S. military said it was withholding soldier's name until it notified next of kin.