TBILISI, Georgia – A grenade hurled in a crowd during last week’s speech by President Bush in the Georgian capital was live and considered a threat against the president, though it failed to explode because of a malfunction, the FBI said yesterday.

In Washington, the White House spokesman said Secret Service agents in Georgia were examining whether security changes were needed, noting that some people at Freedom Square were seen getting around metal detectors at Mr. Bush’s May 10 speech.

Initially, Georgian officials said the Soviet-era grenade was found on the ground, was inactive, and posed no danger to Mr. Bush.

But an FBI agent, Bryan Paarmann, said yesterday that the grenade, wrapped in a dark handkerchief, fell about 100 feet from the podium where Mr. Bush was speaking and “simply failed to function.”

He identified it as a live hand grenade, whereas initial Georgian statements said it appeared to have been an “engineering grenade,” a device that is not designed to spread shrapnel.

“We consider this act to be a threat against the health and welfare of the president of the United States as well as the welfare of the multitudes of Georgian people who turned up for this event,” Mr. Paarmann said.

Mr. Bush spoke to tens of thousands of people in Freedom Square, a main plaza in Tbilisi, as part of a visit aimed at cementing relations between America and the ex-Soviet republic’s new pro-Western leadership. He offered strong support for Georgia’s democratic developments, and the crowd response was overwhelmingly favorable.

President Saakashvili also was on the podium when Mr. Bush spoke, raising the prospect that the grenade could have been directed at him. Mr. Saakashvili, who came to power after the 2003 Rose Revolution that ousted Eduard Shevardnadze, has provoked enmity with anti-corruption initiatives and insistence on restoring control over two de facto independent separatist regions.

Mr. Bush spoke from behind bulletproof glass, and American officials said last week that he had not been in danger.

In fact, the president was not aware of the grenade incident until Secret Service agents on the plane told him about it as he returned to Andrews Air Force Base outside Washington, White House spokesman Scott McClellan said at the time.

No arrests have been made in the case, and police have appealed to the public for videotapes that may contain footage of the incident. A reward equal to $11,000 is being offered.

“Work is going on in a lot of directions; that’s all that can be said,” Inter Ministry spokesman Guram Donadze said.

Mr. McClellan said yesterday the president was updated on the new information Tuesday and given an additional report when the FBI director attended the president’s usual security briefing. “The FBI is working very closely with Georgian authorities to make sure that this is fully investigated,” he said. “We want to see the results of that investigation once it is completed.”