Prime Minister Junichiro Koizumi on Sunday condemned the beheading of a young Japanese backpacker in Iraq and vowed that Japan would not withdraw its troops from the U.S.-led coalition.

The body of Shosei Koda, 24, was identified through fingerprint matches Sunday after it was found on a roadside in central Baghdad the day before. His head had reportedly been wrapped in a U.S. flag and left near his body. Koda, from Japan's southern island of Kyushu, had traveled to Iraq on what he had described to friends as a journey of self-discovery.

Koda's death appeared to further divide Japan over the country's unpopular decision to dispatch 550 noncombat troops to Iraq in its largest military-related mission since World War II. Small vigils and antiwar protests in Koda's name were held Sunday, and analysts said that the release of graphic images of the beheading might fan more domestic opposition to Japan's mission in Iraq.

Earlier this year, five other Japanese kidnapped in Iraq and later released unharmed faced sharp public criticism at home for their recklessness in voluntarily traveling to a global hot spot. Koda's lack of judgment in entering Iraq -- he was reportedly carrying little money and taking few safety precautions -- has also been criticized on the Internet and elsewhere in recent days, even generating harsh comments from the government officials who struggled to save him.

Koda's grief-stricken family said it had received more than 50 phone calls from indignant Japanese critical of their son's trip and the use of tax dollars to try to secure his release. After confirmation of his death, the family apologized for any trouble he might have caused.

"We would like to sincerely apologize for the anxieties we have caused many people," the family said in a statement. "This is the outcome, but we pray that peace will come to the people of Iraq as soon as possible."

Koda left Japan in January for a year abroad, starting his journey in New Zealand. His friends and teachers had reportedly warned him that he was tempting fate by planning to travel to the Middle East.

After reportedly working in Israel for several weeks, he set off for Baghdad by bus from Amman, Jordan, about 10 days ago. He had no hotel reservations there and was apparently unaware that most inns do not take in foreigners off the street. Japanese officials say they believe Koda failed to find lodging and was captured by extremists while wandering around one of the most dangerous sectors of Baghdad with his backpack gear.

Koda was last seen alive begging for his life in a grainy video released Tuesday after being kidnapped by a group linked to Abu Musab Zarqawi, a Jordanian-born insurgent leader in Iraq.

Opposition politicians on Sunday attacked suggestions by Koizumi that the one-year Iraq mission of Japan's Self-Defense Forces, scheduled to end in mid-December, should be extended. "If the SDF were not dispatched, the incident would not have occurred," Katsuya Okada, head of Japan's Democratic Party, said at a news conference.

Japan's pacifist constitution prohibits the SDF from combat-related patrols. The forces have engaged in engineering and transport operations in Iraq and are currently being protected by Dutch forces.

Koizumi vowed that Japan would remain "resolute."

"We cannot lose to terrorism, we must not yield to brute force," he said. "I believe we should continue to support the Iraqi people's efforts to rebuild their country."

Shosei Koda, 24, had left Japan in January for a year of travel abroad.An extra edition of a Japanese newspaper reports the official confirmation of Koda's death in Iraq.