A headless body found Saturday in Baghdad has been confirmed as that of Japanese hostage Shosei Koda, Foreign Minister Nobutaka Machimura said Sunday.

"It is to our great sorrow that after putting all our efforts into securing his prompt release he has become a victim of terrorism," Machimura said.

He told a press conference the confirmation was through match of fingerprint and other physical characteristics.

Machimura described the killing as "unforgivable" and vowed Japan "will firmly go on with the war on terror along with the international community."

Koda, 24, appeared Tuesday on a video footage shown on a website reportedly run by Al-Qaida. The kidnappers gave a 48-hour deadline to the Japanese government to pull the Self-Defense Forces (SDF) out of Iraq, or the hostage will be decapitated.

Japanese Prime Minister Junichiro Koizumi had rejected the demand, saying Japan will not give in to terrorists.

Koda entered into Iraq via Jordan last week. He went there merely to see what is going on, Japanese media said.

He became the sixth Japanese held hostage in Iraq, and the first one killed by kidnappers. Five others were kidnapped earlier this year in two cases, but were later released following mediation of Iraqi clerics. One of the groups also demanded Japan withdraw troops.

Besides Koda, four Japanese had been killed in Iraq by unidentified gunmen in two assaults, two of them were diplomats and the rest were journalists.

Despite the killing, the possibility remains low for Japan to withdraw troops, considering its repeated hard-line assertions on the issue.

There are about 500 ground troops posted in the southern city of Samawah on a rebuilding mission. They are scheduled to return at year end, but the government reportedly is mulling on extending the operation by around another one year.

The beheading was preceded with two previous false alarms as two bodies said to be Asians were found in tandem. The second one was on the verge of confirmation after the US military, the discoverer, told Japan the body bears features identical with those of Koda's. Forensic inspections on Saturday defused worries as apparent discrepances were detected.