President George W. Bush waves to people in the crowd after speaking in Freedom Square, Tbilisi

U.S. Security officials say a grenade thrown toward President Bush during a speech in the former Soviet republic of Georgia last week only failed to explode because it malfunctioned.  That contradicts initial reports that said the grenade was inactive.

The U.S. Federal Bureau of Investigation, FBI, says the hand grenade landed within 30 meters of the president and failed to detonate only because the blasting cap was not struck hard enough.

In a statement from the U.S. embassy in Tbilisi, the FBI says the grenade throwing was a threat against the health and welfare of President Bush as well as Georgian President Mikhail Saakashvili and the thousands of civilians who gathered to hear them speak.

Some of those civilians overran security checkpoints around Freedom Square in the hours before the speech. Both presidents and their wives appeared behind bulletproof glass with a wide opening in front for a microphone.

White House spokesman Scott McClellan says the speech went ahead because the Secret Service at that time did not feel the president's life was in danger.

"The Secret Service takes any number of security precautions when you are talking about a public event that the president is attending, so there are a lot of security steps that they take, and I think you need to keep that in mind when you are talking about this," said Mr. McClellan.

Mr. McClellan says the president was told of the finding that it was a live grenade late Tuesday and was briefed again about the ongoing investigation Wednesday morning.

Mr. McClellan says the president has full trust in the Secret Service and wants to see the results of the joint investigation between U.S. and Georgian authorities once it is complete.

Georgian police initially said the Soviet-era fragmentation grenade was a dud, left in the square to sow panic.

Authorities are offering an $11,000 reward for information to help solve the case.