Updated

The Arabic television channel Al-Jazeera (search) said Saturday that it received the latest videotaped message from Al Qaeda leader Usama bin Laden at its offices in the Pakistani capital.

The tape was dropped off at the gate of the station's office in an envelope on Friday, just hours before it aired, said Ahmad Muaffaq Zaidan (search), Al-Jazeera's bureau chief in Pakistan.

"We received it in Pakistan. ... Somebody dropped it yesterday at the gate," Zaidan told The Associated Press. "The guard brought it to me along with other mail. It was in an envelope, I opened it and it was a big scoop."

Zaidan said he immediately transmitted the tape to Al-Jazeera's headquarters in the Gulf nation of Qatar.

Bin Laden and his top deputy, Egyptian surgeon Ayman al-Zawahri (search), are both believed to be hiding in the mountains that straddle the Afghan-Pakistan border, although there has been no hard evidence of their whereabouts for more than three years.

Zaidan said the fact the tape was received by the station in Pakistan did not necessarily mean that bin Laden and al-Zawahri were in the area.

"It is very difficult to judge," Zaidan said.

Pakistani Interior Minister Aftab Khan Sherpao said authorities have no information about who might have given the network the tape, but he stuck to Pakistan's position that there was no proof bin Laden is in the country.

"We have no idea where they got it," he told AP. "I don't think he is in Pakistan."

Maj. Gen. Shaukat Sultan, the army spokesman, also said he doubted bin Laden was in the country, pointing to intense efforts by the Pakistani military to hunt down Al Qaeda fugitives in the tribal regions of North and South Waziristan, along the border.

"Even if the tape was dropped here, that doesn't mean that he is here," Sultan said. "Nobody knows where he is, but he cannot be in Pakistan's tribal areas because of the presence of so many troops."

While Pakistan's army has been active in the tribal belt, some have questioned their resolve, noting they allowed an Uzbek terror leader to escape after purportedly surrounding him earlier this year.

Talat Massood, a defense analyst and former Pakistani general, said the terror mastermind was likely in the sprawling port city of Karachi or the rugged tribal belt between Pakistan and Afghanistan.

Wherever he is, Massood said, the emergence of the tape shows bin Laden feels pretty secure. In the video, the Saudi millionaire looks to be in surprisingly good health, considering speculation that he has been holed up in a mountain cave for three years, Massood said.

"The fact that he has the courage to come out shows that he feel protected in his surroundings," Massood said, adding that his hearty appearance "shows that he is probably living in reasonable comfort and he is being taken care of."

Meanwhile, the U.S. military in Afghanistan dismissed the new bin Laden tape as "propaganda," and insisted that bin Laden would be caught — but it acknowledged having no fix on the Al Qaeda leader's whereabouts.

"The tape is nothing more than propaganda," U.S. military spokesman Maj. Scott Nelson told reporters. "If you look at Al Qaeda, their organization is being taken down piece-by-piece."

"Although we don't have a timeframe for when bin Laden will be captured, we have full confidence that he will be," Nelson said.

ABC News also received a purported Al Qaeda tape in Pakistan in recent days, this one showing a shrouded man claiming to be an American member of the terror network who threatened more attacks and said U.S. streets would "run red with blood."

Intelligence officials, however, have not been able to verify the tape's authenticity, and officials do not have information linking the video to a specific threat, said an intelligence official, speaking on the condition of anonymity.

They also have not been able to positively identify the speaker.

Both the bin Laden video and the one aired by ABC News carried banners attributing them to the Sahab Production Committee, a purported Al Qaeda propaganda company.