BAGHDAD — The body of a Chaldean Catholic archbishop was found in a shallow grave in northern Iraq on Thursday, two weeks after he was kidnapped by gunmen in one of the most dramatic attacks against the country's small Christian community.

The sad discovery of Archbishop Paulos Faraj Rahho's body came on a day that saw more violence elsewhere in Iraq. A parked car bomb exploded in a commercial district of central Baghdad, killing 18 people and wounding dozens more, police said. Gunmen also killed five members of an anti-al-Qaida group near Tikrit, and a correspondent for a newspaper in Baghdad.

Pope Benedict XVI, President Bush and Iraq's prime minister all deplored the archbishop's death, with the pontiff calling it an "inhuman act of violence that offends the dignity of the human being and harms the peaceful coexistence of the dear Iraqi people."

Since the U.S.-led invasion in 2003, Iraqi Christians have been targeted by Islamic extremists who label them "crusaders" loyal to U.S. troops. Militants have attacked churches, priests and businesses owned by Christians. Many Christians have fled the country, a trend mirrored in many dwindling pockets of Christianity across the Islamic world.

Rahho, 65, was seized on Feb. 29, just minutes after he delivered a mass in Mosul, a city considered by the U.S. military the last urban stronghold of al-Qaida in Iraq. Three companions were killed.

After two weeks of searching and praying, officials at the archbishop's church received a phone call Wednesday from the captors. The caller told the officials that Rahho had died and where to find his body, Monsignor Shlemon Warduni, the auxiliary bishop of Baghdad, told The Associated Press.

It was not immediately clear if Rahho was killed or if he died of an illness. Shortly after his abduction, church officials had said they were especially worried because the archbishop had health problems, which they did not identify.

A Mosul morgue official, speaking on condition of anonymity for security concerns, said Rahho's body had no bullet holes. The official said police found the body in an early stage of decomposition under a thin layer of dirt just north of the city, suggesting that Rahho had been dead for a few days.

There have been no claims of responsibility for the archbishop's kidnapping or his death.

The Chaldean church is an Eastern-rite denomination that recognizes the authority of the pope and is aligned with the Roman Catholic Church. Chaldean Catholics make up a tiny minority of the current Iraqi population but are the largest group among the less than 1 million Christians in Iraq, according to last year's International Religious Freedom Report from the U.S. State Department.

Iraqi Prime Minister Nouri al-Maliki said in a statement: "We condemn and denounce this ugly crime and consider it as an aggression that aims to ignite strife among ... the Iraqi people."

In Washington, Bush said he sent his condolences to the Chaldean community and the people of Iraq.

"I deplore the despicable act of violence committed against the Archbishop of Mosul," the president said in a statement. "The terrorists will continue to lose in Iraq because they are savage and cruel. Their utter disregard for human life, demonstrated by this murder and by recent suicide attacks against innocent Iraqis in Baghdad and innocent pilgrims celebrating a religious holiday, is turning the Iraqi people against them."

U.S. and Iraqi forces have been trying to root out extremists from Mosul, a violent city 225 miles northwest of Baghdad.

In an interview in November with AsiaNews, Rahho said the situation in Mosul was not improving and "religious persecution is more noticeable than elsewhere because the city is split along religious lines."

Thursday's bombing in Baghdad, meanwhile, killed 18 people near a bridge in Tahrir Square, a district of clothing shops just outside the heavily fortified Green Zone, a police official said.

In other violence, five members of an Awakening Council were killed when unidentified gunmen attacked two separate checkpoints near Tikrit, 80 miles north of Baghdad. Nine others were wounded in the attacks.

Unknown gunmen also killed a correspondent for a Baghdad newspaper.

Qassim Abdul-Hussein al-Iqabi, 36, was shot while walking in Baghdad's largely Shiite Karradah neighborhood, according to a police official. Both police officials spoke on condition of anonymity because they were not authorized to release information.

Excluding the latest death, the New York-based Committee to Protect Journalists has recorded at least 127 journalists and 50 media support workers killed since the U.S.-led war began in March 2003.

Associated Press writers Ryan Lenz in Baghdad and Alessandra Rizzo in Rome contributed to this article.