A Kurdish journalist gunned down in the northern city of Kirkuk was the 136th reporter killed in Iraq since the US-led invasion of Iraq five years ago, a New York-based journalists' group said Saturday. Col. Taha Al-Din of Kirkuk police said Diyar Abbas Ahmed, a journalist with Iraq Eye media, was assassinated Friday in the city center. Ethnic and religious tensions have risen in the city, which has been the site of a tense standoff between Arabs and Kurds. Kurds want to incorporate Kirkuk into their semiautonomous region in the north. Iraq's government has been stalled for months over the future status of the oil-rich city. The Committee to Protect Journalists called on Iraqi authorities to track down Ahmed's killers and bring them to justice. It said four journalists have been killed in the Kirkuk area since 2003. According to its website, Iraq Eye provides news, market research, public relations and other services. Meanwhile, the governor of Iraq's northern Ninevah province says 500 Christian families have fled their homes in Mosul in the past last week. Duraid Mohammed Kashmoula says the families have left for churches, monasteries and the homes of relatives in nearby Christian villages and towns. Kashmoula said Saturday that seven Christians have been killed in the last week. Local Christian leaders have said the attacks amount to a “campaign of killings” and displacement. The Christian community has been estimated at 3 percent of Iraq's 26 million people, or about 800,000 people. Islamic extremists have frequently targeted them since the 2003 US