Bin Laden's video appearances

7 October: Warns US will never be safe 3 November: Attacks UN and Arab leaders 14 December: US releases video it says shows Bin Laden 'boasting' about 11 September attacks 26 December: Bin Laden says terrorism 'blessed'

Bin Laden is thought to suffer from a kidney complaint, and months of living on the run evading US attacks may have taken its toll.

With unconfirmed reports that Bin Laden may have been killed by US bombing raids, correspondents said the tape should at least prove when he was last alive.

The tape seemed to have been recorded at the end of November or beginning of December.

Dry lips

Bin Laden refers to a US air strike on a mosque in the Afghan town of Khost as happening "a few days ago".

The most likely date for that attack was 16 November, when a US laser-guided bomb missed its target in Khost and damaged a mosque.

Some believe Bin Laden was killed by US bombing

Bin Laden also said he was speaking three months after the 11 September terrorist attacks on the US, and two months on from the start of US air strikes.

With his Kalashnikov at his side, Bin Laden appears to wet his lips several times while speaking.

His every gesture is being pawed over for meaning, and correspondents say his lips would be dry during the Muslim fasting month of Ramadan, which ended on 15 December.

If the tape was recorded early in December, it would have coincided with the Taleban's surrender of their stronghold Kandahar, and Bin Laden's reported flight to the eastern Tora Bora mountains.

Since then there have been regular unconfirmed reports that Bin Laden is dead, alive, still in Afghanistan or escaped to Pakistan.

Pakistan's leader General Pervez Musharraf was the latest to add to the speculation when he said he was "reasonably sure" Bin Laden was killed by US bombing at Tora Bora.

That has prompted some US officials to ask if the latest video is a code to his followers that he has been killed, the Associated Press reported, quoting unnamed sources.

It is not clear from the segment of the tape released so far where Bin Laden was speaking from.

But as further proof of how every glimpse of him spawns speculation, analysts pointed out that he only seemed to raise his right hand when talking to camera - even though he is thought to be left handed - prompting the question, why?