A group in Iraq believed led by Islamic militant Abu Musab al-Zarqawi has taken a Japanese man hostage, and is threatening to behead him if Tokyo does not remove its troops from Iraq within 48 hours. A video of the hostage was posted on the Internet and aired on an Arabic satellite television network.

Japanese Prime Minister Junichiro Koizumi established a crisis center Wednesday morning after learning that a 24-year-old Japanese man was being held hostage in Iraq.

Mr. Koizumi says Japan will not adhere to the demands of the militant group, to pull its 500 non-combat troops out of Iraq.

Mr. Koizumi says he wants his government to do all it can to free the hostage, but removing the Self Defense Forces from southern Iraq is not an option.

The hostage was identified by his family as Shosei Koda, after a video shot by the captors was shown on Japanese television.

The family says Mr. Koda had recently been on a working holiday in New Zealand. In a video posted on the Internet, the group holding Mr. Koda says he is an "element following the Japanese troops" and that he entered Iraq after visiting Israel and Jordan.

Speaking in broken English and Japanese on the video, Mr. Koda addresses Mr. Koizumi, saying his captives asked why Japan broke the law and sent troops to Iraq.

Mr. Koda apologized to the prime minister, saying he is sorry to put his head in Mr. Koizumi's hands.

One of the militants on the tape says that if the troops are not removed within 48 hours, the Japanese captive will meet the same fate as previous hostages. Insurgents in Iraq have beheaded hostages from a number of countries, including South Korea, Britain and the United States.

There have already been Japanese casualties in Iraq. Two freelance journalists were killed in an attack near Baghdad in May, and two diplomats were fatally shot last November.

Another five Japanese nationals were taken hostage in two separate cases in April. All five were later released unharmed.