Usama bin Laden recorded his threats against the United States two weeks ago and took such elaborate precautions to protect his security that he taped his message in pieces — sometimes speaking over the phone, officials said yesterday.

That is among the conclusions of technical experts of the CIA and the National Security Agency who began analyzing the bin Laden audio tape almost immediately after it appeared on the Arabic news channel Al-Jazeera on Tuesday.

Intelligence officials told The Post there is no doubt the voice on the tape was bin Laden's, confirming, after a year of silence, that the elusive terror master is alive, although not necessarily in good health.

While more work is being done, the analysis concluded:

• Bin Laden recorded his message two weeks ago because it praises the Oct. 28 assassination of U.S. diplomat Laurence Foley in Jordan but gives no mention of last Friday's U.N. Security Council vote on weapons inspections in Iraq — a subject bin Laden almost certainly would have mentioned

• The recording was done in pieces in different locations, and bin Laden sometimes was speaking by phone or having the tape re-recorded over the phone.

• While the voice, flowery Arabic phrases and menacing rhetoric are clearly bin Laden's, his sentences are shorter and he sometimes appears out of breath, a possible sign he is ailing.

• U.S. officials believe bin Laden chose to make an audio tape rather than his usual practice of appearing on video because he does not want to be seen — either because he is too sickly or has altered his appearance.

"The tape tells us that he's feeling confident enough to re-emerge, but not confident enough to appear visually," said Vincent Cannistrarro, former CIA counterterrorism director.

The Saudi-born millionaire fanatic was last placed in Tora Bora in Afghanistan last December, leading his terrorist fighters against a massive air and ground assault on his underground mountain fortress.

After that, he disappeared and is believed to be hiding in the mountainous no-man's land along the Afghan-Pakistan border, where he enjoys widespread support from local tribes, according to U.S. intelligence officials.

Ahmad Muffaq Zaidan, an Al-Jazeera journalist based in Pakistan, said he received the latest bin Laden tape after he received a phone call from an Al Qaeda agent on Tuesday and met with him in Islamabad.

"He only gave me the cassette, and in half a minute he disappeared," Zaidan said.

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