Bush has broken his silence over the missing explosives in Iraq, dismissing presidential rival John Kerry’s allegations of incompetence as “wild charges.”

As he campaigned in three crucial states ahead of Tuesday’s election, Bush said US forces were investigating the disappearance of 350 tonnes of explosives, and that Kerry’s comments were irresponsible.

“The senator is making wild charges,” he said. “This investigation is important and ongoing, and a political candidate who jumps to conclusions without knowing the facts is not a person you want as your commander in chief.”

Amid frequent and deadly attacks on US soldiers in Iraq, Kerry has seized on the missing explosives as a symptom of bad planning for the post-war reconstruction and said the Bush team was not being honest.

“Your administration was warned, you were put on notice but you didn’t put these explosives on priority lists, you didn’t think it was important,” Kerry said from Massachusetts.

“You didn’t give the troops the instructions they need, you didn’t guard the ammunition dumps and now our troops are at greater risk.

“This is a growing scandal and the American people deserve a full and honest explanation of how it happened,” Kerry said.

It was unclear when the explosives went missing. The Pentagon has said it did not know when they disappeared, and Bush said US forces were looking into whether it happened before US troops arrived.

But the International Atomic Energy Agency (IAEA) said this week that the explosives went missing from the site, south of Baghdad, after US-led forces toppled Saddam in April 2003.

Mohammed al-Sharaa, who heads Iraq’s science ministry’s site monitoring department, said “it is impossible that these materials could have been taken from this site before the regime’s fall.”

He said he and other officials had been ordered a month earlier to insure that “not even a shred of paper left the sites.”

Meanwhile in the US, six days before the election the race for the White House remained unpredictable.

A Washington Post daily tracking poll showed Kerry adding a point to lead Bush 50-48. Zogby International had Kerry picking up two points to narrow Bush’s lead at 47-48 percent.

A third survey by the Rasmussen group showed Bush on top with 49 to 47 percent.