U.S. intelligence officials will try to determine the authenticity of a new audio tape said to be from former Iraqi leader Saddam Hussein. The speaker on the tape encourages Iraqis to help fighters who have been attacking U.S. troops.

Even if the tape proves that Saddam Hussein is alive, White House spokesman Ari Fleischer says it does nothing to dampen the accomplishments of the U.S. led invasion.

Speaking on the sidelines of a presidential speech marking U.S. Independence Day, Mr. Fleischer says the U.S. Central Intelligence Agency is analyzing the tape to determine whether it is really Saddam.

"Regardless of whether it is him or not," he said. "Regardless of whether he is dead or alive, the mission in terms of getting rid of the regime has been achieved. Iraq, however, still is a dangerous place but we are going to do a careful analysis of this tape."

In the first broadcast Friday by al-Jazeera television, the tape calls on Iraqis to protect resistance groups that are fighting coalition troops. The speaker who claims to be the former Iraqi leader says he and his followers are still inside the country directing attacks against Americans.

Uncertainty about Saddam's whereabouts are thought to be encouraging attacks against coalition troops, with Washington now offering a $25 million reward for the former leader's capture or proof of his death.

Mr. Fleischer says the White House believes many Iraqi scientists are reluctant to come forward with information about the country's weapons program because they still fear Saddam and his sons, none of whom have been captured.

The immediacy of the threat from Iraqi weapons of mass destruction was one of the biggest reasons President Bush gave for invading the country. Yet more than two months after Mr. Bush declared an end to major combat, none of those weapons has yet been found.

Without mentioning President Bush by name, the speaker on the audio tape questions his justification for the war by asking, "Where are these weapons of mass destruction?"

President Bush maintains that evidence of illegal chemical and biological weapons in Iraq will be found. In his Fourth of July speech, Mr. Bush said U.S. force is making the world safer by preventing terrorists from acquiring weapons of mass destruction.

"Without America's active involvement in the world, the ambitions of tyrants would go unopposed and millions would live at the mercy of terrorists," he said. "With America's active involvement in the world, tyrants learn to fear and terrorists are on the run."

If the tape is authenticated, it would be the first definitive proof that Saddam survived the war. U.S. intelligence analysts have studied other tapes supposedly made by the former Iraqi leader but because of the poor quality of the recording, they have not been able to make any conclusive judgments.