(AFP) -- The leaders of Iraq's Christian minority on Thursday called on the country's beleaguered government to protect their community from attacks by Al Qaeda-inspired Muslim extremists.

In a joint statement, Patriarch Mar Dinka IV of the Catholic Assyrian Church of the East and the Chaldean Catholic Patriarch Emmanuel Delly of Babylon said Baghdad's remaining Christians were facing persecution.

They blamed the so-called "Islamic State of Iraq", an alliance of Islamist insurgent groups that serves as an Al-Qaeda front, for much of the violence.

"Christians in a number of Iraqi regions, especially those under the control of the so-called Islamic State of Iraq, have faced blackmail, kidnapping and displacement," the statement said.

The churchmen expressed surprise that Al-Qaeda's influence has "reached parts of Baghdad while the government has kept silent and not taken a firm stance to stop their expansion."

Before the US invasion in March 2003 there were estimated to be around 800,000 Christians in Iraq, around three percent of the otherwise largely Muslim population, living mainly in urban centres such as Baghdad.

Although there were some attacks on churches in the immediate aftermath of the fall of Saddam Hussein, Iraq's Christians were not especially targeted while rival Sunni and Shiite Muslim factions went to war.

As a relatively wealthy community, however, many Christians fell prey to kidnap and ransom gangs and many -- probably more than half -- of them have fled the country or moved to the relative safety of Iraqi Kurdistan.

Now there are reports that Salafist groups such as Al-Qaeda, fundamentalists who believe Islam can be renewed by returning to the values of the era of the Prophet Mohammed, are targeting Christians on purely sectarian grounds.

In recent weeks a "fatwa" or Muslim religious decree has been issued by extremists ordering Christians to flee Dura, a southern suburb of Baghdad which is a hotbed of Sunni insurgent groups.

"We see that today we are being sent from our houses and forcibly displaced from our homeland and alienated from our brothers with whom we lived together," Delly complained this week in a sermon, according to the Al-Mutamer newspaper.

"I hereby send a plea in the name of all Christians to officials and to all those whose power is in their hands to bring about peace, security and stability among the sons of the homeland," he was quoted as saying.

In addition to calling on Prime Minister Nuri al-Maliki's government to protect them, the patriarchs also urged the United Nations to intervene.