BAGHDAD -- Hundreds of Christians are fleeing Mosul in the wake of a string of killings that appear to be singling out Christians in the northern Iraqi city, where many had taken refuge from persecution in other parts of the country.

At least 11 and perhaps as many as 14 Christians have been killed in Mosul since the end of August, according to government officials and humanitarian groups. The victims have included a doctor, an engineer, two builders, two businessmen and a 15-year-old boy, who was shot dead in front of his house. In the last week alone, seven Christians were killed.

On Friday, a pharmacist was shot to death by a man who pretended to be an undercover police officer and asked for the man's identification card, said Khisroo Koran, deputy governor of Nineveh Province, which is in northern Iraq. Mosul is the province's capital.

Louis Sako, the archbishop of the Chaldean Catholic Church in Kirkuk, said Friday that the killings were an example of "a campaign of cleansing, killing and threatening" that Christians faced in Iraq.

The shootings in Mosul come on the heels of an angry dispute over the Iraqi Parliament's decision to drop a provision in an earlier version of the provincial elections law that ensured political representation for Christians and other minorities. Lawmakers approved the legislation, without the provision, on Sept. 24.

Christians have held demonstrations to protest the Parliament's action in Baghdad and in Nineveh Province -- where about 250,000 Christians live, about 50,000 of them in Mosul.

At one demonstration in Nineveh, protesters held up signs demanding the creation of a 19th province governed by Christians that would be linked to the Kurdish region in the north, according to William Warda, an Iraqi journalist and chairman of the Hammurabi Human Rights Organization, which is based in Baghdad.

Earlier this week, a panel led by President Jalal Talabani approved the provincial elections law but urged the Parliament to reconsider the issue of representation for minorities and to take a separate vote on the section that had been dropped. The lawmakers decided instead to form a committee to draft a new law after they determined which groups should be designated as minorities and how many council seats should be reserved for them.

Several Iraqi Christian leaders said Friday that the killings in Mosul might be tied to the protests held last week and the demands for a semiautonomous province.

Mr. Koran said that fliers had recently appeared on the streets in Mosul threatening Christians and warning them to leave the city. He blamed insurgents and people he called "nationalist extremists" for the killings. Others have blamed the Kurds, who control much of the east side of Mosul and the region surrounding the city.

In the last week, more than 150 families have left Mosul for towns northeast of the city like Bartilla, Tallkayf and Qaraqosh, which are predominantly Christian, according to provincial officials.

Jawdat Toma Yousef, who owns a store selling wholesale underwear in the market in central Mosul, said that he and his family had moved away after his brother, who also had a wholesale store, was killed last Saturday around noon.

"Me and another brother closed our store at 12:15 that day, and then after that, four guys came to the market and one of them shot my brother, Hazzem, and killed him in front of his son," Mr. Yousef said.

He said that after the attack, 18 members of his family were living in a small rented house in Qaraqosh. "We could not bring anything with us except our clothes and our money," he said. "We left Mosul immediately after we buried my brother's body."

There have been kidnappings and killings of Christians in Baghdad and in other parts of Iraq. In Mosul, which has not been immune to the violence, a spate of killings last year terrified Christian residents, and this February, Archbishop Paulos Faraj Rahho, the leader of the Chaldean Catholic Church in Mosul, was kidnapped and his body was found in March buried in the southeast of the city.

In the towns of the Nineveh Plain, northeast of Mosul, where attacks on Christians have been much more rare, many Christians have taken refuge. The towns are mostly Christian, and the area is dotted by ancient Assyrian and Chaldean villages and monasteries built during the time of Prophet Muhammad.

But even in the Nineveh Plain, tensions have been simmering since 2003, when Kurdish security forces moved into the region. Kurdish flags still fly at the entrances to the towns and checkpoints are controlled by the Peshmerga, the Kurdish security forces.

The Christians are split between those who want to remain under the central Iraqi government and those in favor of a semiautonomous province tied to the Kurdish region.

Recently, attacks against Christians have decreased in many parts of Iraq, along with other violence. "The reality is that vengeance and the attempts against Christians have moved to the north, and that is really difficult, really difficult, because that is the precise place they ran for safety," said Canon Andrew White, the Anglican vicar of St. George's Church in Baghdad.

In other developments, Prime Minister Nuri Kamal al-Maliki went to Najaf on Friday to visit Grand Ayatollah Ali al-Sistani, the country's most influential Shiite religious leader. Mr. Maliki said afterward that Mr. Sistani would not oppose a security agreement governing the continued presence of American troops in Iraq, as long as the government gave its assent and Parliament approved the agreement.

Earlier this week, Deputy Secretary of State John D. Negroponte and Iraq's foreign minister, Hoshyar Zebari, said negotiators were close to resolving the issues that have stood in the way of an agreement.

The Americans and the Iraqis are under pressure to complete the security agreement before Dec. 31, when a United Nations mandate that serves as the legal basis for the presence of American troops expires.

In Sadr City on Friday, thousands of followers of the rebel Shiite cleric Moktada al-Sadr shouted anti-American slogans as they marched along a funeral convoy carrying the body of Saleh al-Ugaili, a member of Parliament representing the Sadrist party who was killed on Thursday by a roadside bomb.

In a statement, Mr. Sadr blamed the United States for Mr. Ugaili's death. The United States Embassy and the American military condemned the killing as "an attack on against Iraq's democratic institutions."

Also on Friday, a car bomb exploded in the Abu Dshir neighborhood of Baghdad, killing at least 12 people.

Reporting was contributed by Campbell Robertson from Qosh, Iraq; Atheer Kakan, Tareq Maher and Riyadh Mohammed from Baghdad; and an Iraqi employee of The New York Times from Kirkuk.

By Erica Goode And Suadad Al-Salhy
New York Times