The body of a South Korean hostage was found west of Baghdad today after a Muslim extremist group carried out its threat to kill him to back a demand for the withdrawal of South Korean troops from Iraq.

The execution of Kim Sun Il, a 33-year-old translator for a Korean firm in Iraq, was reported by the al-Jazeera Arabic satellite television network, which said it had received a videotape that confirmed the killing. Kim's death was also confirmed by the South Korean Foreign Ministry, which reported that his body was found by the U.S. military late this afternoon between Baghdad and Fallujah, a hotbed of rebellion about 35 miles west of the capital.

A group calling itself Jamaat al Tawhid wal Jihad (Monotheism and Jihad) abducted Kim last Thursday near Fallujah and threatened to kill him at sundown Monday unless South Korea pulled out its 670 troops -- mostly military medics and engineers -- and canceled plans to send 3,000 more soldiers starting in August. The group reportedly is headed by Abu Musab Zarqawi, a Jordanian terrorist whom U.S. officials say has links to the al Qaeda network of Osama bin Laden.

A videotape aired by al-Jazeera Monday showed Kim, an Arabic speaker and evangelical Christian, pleading for his life. Kim was employed by a South Korean firm that supplies goods to the U.S. military in Iraq. He had worked in Iraq for about a year.

A videotape played on al-Jazeera today showed Kim blindfolded and kneeling in an orange jumpsuit similar to one worn by U.S. businessman Nicholas Berg when he was beheaded by Zarqawi's group on a videotape that was broadcast in May.

Standing behind Kim in the latest video were five hooded men, one of whom read a statement. Another wore a large knife on his belt.

The speaker blamed South Korean citizens for not doing enough to pressure their government to pull out of Iraq.

"This is what your hands have committed," he said. "Your army has not come here for the sake of Iraqis, but to serve the cursed America."

The video as aired by al-Jazeera did not show Kim being beheaded, but the station said the killing was carried out.

In Washington, President Bush said he hopes that South Korean President Roh Moo Hyun "would understand that the free world cannot be intimidated by the brutal actions of these barbaric people."

At a photo opportunity at the White House with the visiting Hungarian prime minister, Bush said, "They are trying to get us to withdraw from the world so they can impose their dark vision on people. . . . In order to impose their vision, they want us to leave. They want us to cower in the face of their brutal killings. And the United States will not be intimidated by these people."

Earlier, White House spokesman Scott McClellan said, "There simply is no justification for those kinds of atrocities that the terrorists carry out." He said that "the barbaric nature of the terrorists" was shown by the recent beheading of an American civilian, Paul Johnson, in Saudi Arabia by a group connected with al Qaeda.

The group that killed Kim had reportedly agreed earlier to delay the execution, according to a security firm that attempted to mediate his release.

In the face of the group's demands, President Roh stood by plans to dispatch the main contingent of 3,000 troops to Iraq starting in August, even as the 24-hour deadline passed with no official word of Kim's fate.

However, Choi Seung Kap, president of NKTS -- a Seoul-based international security firm that has a contract to train Iraqi police and was trying to facilitate talks between the captors and Kim's private employers -- said in a telephone interview that Kim was alive and that the militants had agreed to negotiations after the intervention of Iraqi clerics.

Three Japanese hostages taken in the same area of Iraq in April were freed after religious leaders intervened on their behalf.

"Religious leaders are working together to deal with the militants; [the clerics] requested the militants to delay their plans so that we could come up with a negotiated solution," Kap said before the killing of Kim became known. Kap declined to outline the captors' demands.

The Dubai-based satellite television network al-Arabiya also reported Tuesday that the kidnappers had agreed to extend the deadline, citing an unnamed source.

South Korean officials said that a high-level diplomatic delegation from Seoul was in the region Tuesday and was working with authorities from the United States, the United Nations and Iraq to secure Kim's release.

Kim, a devout evangelical Christian who learned Arabic in hopes of becoming a missionary in the Middle East, was kidnapped while working as a translator for South Korean contractor Gana General Trading Co., which supplies food and clothes to the U.S. military in Iraq. South Korean officials said Kim was captured near Fallujah on June 17.

On Tuesday, the Seoul government issued a separate evacuation order for 22 other South Korean civilian contractors in Iraq. Foreign Minister Ban Ki Moon and other top politicians appealed to the Arab world for support during a half-hour interview with al-Jazeera. Ban asserted that the South Koreans are there only to help build roads and assist the wounded. Additional plans to send 3,000 troops -- finalized here on Friday, three days before the video of Kim was released -- will make South Korea the third largest contributor to forces there, after the United States and Britain.

"South Koreans are a friend of the Iraqi people," Ban said "There is no reason for Kim's kidnapping. The whole county is in shock over the news on the hostage-taking of an innocent civilian."

The involvement in Iraq is widely unpopular in South Korea, with polls showing at least 56 percent of the population strongly opposed to the troop dispatch. Hundreds of protesters, including Kim's family, took to the streets for a second day today -- in somewhat smaller numbers than Monday -- to demand a withdrawal from the Iraq mission. A group of politicians from the left-leaning Uri Party aligned with President Roh additionally vowed to join with almost two dozen opposition lawmakers to present legislation in the National Assembly on Wednesday seeking to scrap the troop deployment.

The participation in Iraq, however, is viewed as essential to shoring up Seoul's relations with the United States, which have grown strained in recent months as South Korea has improved ties with North Korea even as Washington has sought to isolate the Pyongyang government because of its avowed nuclear weapons programs.

Analysts in South Korea were skeptical that the legislators could win enough votes to overturn the deployment.

Special correspondent Joohee Cho contributed to this report.