SAMAWAH, Iraq -- Ground Self-Defense Force personnel heard explosions and found evidence of possible mortar rounds having hit near their base here Wednesday night in what may have been the first attack aimed at Japanese troops in Iraq.

GSDF officers said Thursday that three blasts were heard at 11:13 p.m. at the base outside the southern Iraqi city. Marks indicating that mortar shells or rocket-propelled grenades had hit the ground were found in two places about 300 meters north of the camp, the officers said.

Iraqi police confirmed that two shells had hit near the camp.

Prime Minister Junichiro Koizumi on Thursday called the incident "a terrorist attempt aimed at kicking Japanese troops out of Iraq."

"Terrorists will do anything to throw the situation into chaos," he said.

Defense officials in Tokyo later said the GSDF troops found one of the shells, and it was about 6 cm to 8 cm in diameter. The Defense Agency later said it was almost certain that one of the shells was a phosphorous smoke bomb.