The U.N. nuclear agency says it had expressed concern to the United States in April 2003 about the security of explosives at a facility south of Baghdad.
A spokeswoman for the International Atomic Energy Agency (Melissa Fleming) said the warning about the al-Qaqaa facility came shortly after looters had swept through Iraq's Tuwaitha nuclear complex.
She says the IAEA's chief Iraq inspector told U.S. officials that the agency was concerned about the security of the high explosives at al-Qaqaa, the main high explosives storage facility in Iraq.
The IAEA says 342 (metric) tons of explosives went missing from al-Qaqaa after April 2003 due to looting and lack of security.
President Bush said Wednesday that officials are investigating a number of possibilities, including the possibility that the explosives were moved before U.S. troops arrived at the site.