Japan's defense chief on Sunday said that Japanese troops could remain in Iraq until late 2005, a year longer than their current mandate.

Some 500 Japanese troops are on a humanitarian mission in the southern Iraqi city of Samawah (search). Their mandate expires Dec. 14, and the government hasn't yet decided if the troops will stay.

Asked about a potential pullout, Defense Minister Yoshinori Ono (search) said several factors had to be considered, including whether the troops had fulfilled their mission to help rebuild the country.

"Another factor to consider is that a mission by multinational troops expires next December — that could be one cutoff point," Ono said on NHK television.

Ono was referring to a December 2005 deadline set by a United Nations Security Council resolution that included steps to establish a constitutionally based government that would end the mandate of the U.S.-led multinational military force in Iraq.

Many in Japan strongly oppose the country's troop deployment, and the issue has been debated fiercely in parliament in recent days.

Fears for the safety of the troops have increased, due in part to recent mortar attacks on the Japanese camp. The government has insisted the area still qualifies as a noncombat zone, meeting legal restrictions authorizing the troop dispatch. The opposition argues that all of Iraq is a war zone.

Japan's constitution bars the use of military force in settling international disputes. It also pledges not to maintain a military, although the government says the nation can possess self-defense forces.

Prime Minister Junichiro Koizumi has expressed support for keeping the Japanese troops in Iraq but has said no decision will be made until next month.