Baghdad, Iraq ? Civilians shopping at street markets, worshipping at mosques and mourning at funerals have become the prime target of insurgents in a two-week spree of carnage that many people think is linked to efforts by foreign extremists to plunge Iraq into civil war.

At least 489 people, most of them civilians, have been killed by bombings and other insurgent attacks since Iraq’s new government was announced by Prime Minister Ibrahim al-Jaafari on April 28.

Now, with the bodies of 50 men found shot to death by unknown assailants and dumped across the country over two days, fears are rising that foreigners like Abu Musab al-Zarqawi may be making headway in their campaign to turn Iraq’s fractious communities against each other.

There are worries the unexplained killings in Baghdad and other cities could be a result of angry Shiite and Sunni Muslims retaliating against each other’s communities in frustration over two years of unrelenting insurgent attacks.

Religious leaders also have been singled out. Shiite cleric Qassim al-Gharawi died in a drive-by shooting in western Baghdad last week. Quraish Abdul Jabbar, a Sunni cleric, was reported shot dead and his body dumped behind a mosque in northeastern Baghdad on Monday.

“We are approaching a situation that is unstable, of a war of all against all, complete chaos, where the government is ineffective, the security is ineffective, and anybody can be killed at any time by anybody,” said Kenneth Katzman, an expert on the Persian Gulf region with the U.S. Congressional Research Service.

The Jordanian-born al-Zarqawi, leader of Al-Qaida in Iraq, made his intentions clear in a letter obtained and released last year by the U.S. government saying that causing sectarian fighting between Shiite and Sunni was the best way to undermine American policy in Iraq.

Most of the insurgent attacks aimed at civilians have been in neighborhoods whose residents are predominantly from Iraq’s Shiite Arab majority or their Kurdish allies. Many insurgents are thought to be from the formally dominant Sunni Arab minority, but many Iraqis blame foreign extremists for the assaults on civilians.

“This shows that the terrorists are in their last period. They weren’t able to violate the security zone and therefore they started targeting schools, markets in order to kill civilians,” the new defense minister, Saadoun al-Duleimi, said at a news conference Monday.

Iraqis flee the scene of a car bomb explosion near a market in eastern Baghdad, Iraq, in this May 12 photo. At least 17 people were killed when the car bomb blast ripped through a market in a Shiite area of Baghdad. Some analysts believe that the escalating sectarian violence is pushing Iraq to the brink of a civil war.

Al-Duleimi, a Sunni Arab, said insurgents killed 230 civilians last week alone, while only 13 Iraqi soldiers and policemen were slain.

The government’s efforts to quell insurgent violence and keep Iraq’s religious and ethnic communities from splitting could be complicated by the close relationship between the Interior Ministry, headed by Shiite leader Bayan Jabr, and the Badr Brigades, the militia of Iraq’s leading Shiite group, the Supreme Council of the Islamic Revolution in Iraq.

Concern was raised when the militia, once regarded as terrorist by U.S. officials, cooperated with security forces to capture four Palestinians and an Iraqi wanted for a bombing Thursday that killed at least 17 people at market in a Shiite neighborhood of Baghdad.

Al-Duleimi, the defense minister, has said he won’t merge militias such as the Badr Brigades and the Kurdish Peshmerga into Iraq’s army. The United States has called for the militias to be disbanded.

Despite the violence and communal frictions, Katzman, the analyst at the Congressional Research Service, doesn’t yet see Iraq tumbling into a sectarian war.

“Some would define this as some kind of civil war, but we don’t yet have entire distinct camps across the country opposing each other,” he said.