WASHINGTON - U.S. intelligence analysts said yesterday that they had concluded that the voice on an audiotape that emerged last week is Osama bin Laden's, and that the tape was made quite recently.

The authentication of the tape, while not unexpected, is significant in that it represents an official determination after almost a year of doubt that the terrorist leader is still alive.

The conclusion follows days of intensive analysis of the tape by experts at the CIA and the National Security Agency. The analysis included studies by linguists and translators familiar with bin Laden's voice.

The experts had said earlier that the tape appeared genuine, but until yesterday had refrained from saying so definitively.

At a news briefing, White House spokesman Scott McClellan conceded that the genuineness of the tape "cannot be stated with 100 percent certainty," but he reiterated that intelligence officials believe that it is real.

Until the tape was broadcast on Al-Jazeera, the Arabic satellite television network, there had been speculation about whether bin Laden, the presumed mastermind of the Sept. 11 terrorist attacks, died in the U.S.-led bombing in Afghanistan. Because the tape was a voice recording and not a videotape, like those of a year ago, there has been conjecture that bin Laden's health has deteriorated or that he is injured - and reluctant to show himself.

In the tape, the voice now concluded to be that of bin Laden reads a statement promising new terrorist acts against the United States and its allies. The voice mentions the takeover of a Moscow theater by Chechen rebels in late October, the bombing of a nightclub in Indonesia on Oct. 12 and other recent events.

Ahmad Muaffaq Zaidan, the reporter who gave the tape to Al-Jazeera, said it had been given to him Tuesday in Islamabad, Pakistan, by a bin Laden emissary.