The Defense Agency on Thursday ordered the Northeastern Army of the Ground Self-Defense Force to prepare to head to southern Iraq to take over Japan's humanitarian aid mission there -- an indication the government is prepared to extend troop deployment beyond its one-year mission.

When they receive the dispatch order, which is likely to come in mid-November, about 600 troops will be sent to the southern Iraqi city of Samawah on a three-month mission of reconstruction and water-purification work.

The GSDF troops rotate every three months.

The preparation order, which requires the Northeastern Army headquarters in Sendai, Miyagi Prefecture, to form a unit for Iraq, comes before the government has announced its decision whether to extend SDF deployment beyond the Dec. 14 end to its one-year commitment.

The GSDF camp in Samawah, which the government has called "a relatively safe area," has had several threats to its security in recent days.

A rocket, fired by an unidentified group, damaged a storage container inside the camp Sunday, just 10 days after another rocket landed inside the camp perimeter -- the first attack on the camp since it was established in April.

Prime Minister Junichiro Koizumi said after the latest attack that security in Samawah "will continue to be unpredictable" and that he has not decided whether to extend the deployment.

The opposition Democratic Party of Japan is demanding troop withdrawal, saying Samawah is no longer a noncombat zone as has been claimed by the Japanese government. Koizumi said he would decide whether to extend the mission after considering various factors, including public opinion.

Under a special law that paved the way for the dispatch of the SDF to Iraq, Japanese troops can only be deployed to noncombat areas in compliance with Japan's war-renouncing Constitution.