The voice, attributed to bin Laden and apparently addressing Americans, said: "Operations are under preparation, and you will see them on your own ground once they are finished, God willing."

But the voice on the tapealso offered a truce: "We do not object to a long-term truce with you on the basis of fair conditions that we respect."

The tape, broadcast by Aljazeera on Thursday evening but dated last December, comes after a year of silence from the al-Qaeda leader.

Bin Laden said: "My message to you is about the war in Iraq and Afghanistan and the way to end it. I had not intended to speak to you about this issue, because, for us, this issue is already decided on: diamonds cut diamonds.

"Praise be to God, our conditions are always improving and becoming better, while your conditions are the opposite of this.

"However, what prompted me to speak are the repeated lies of your President Bush in his comment on the outcome of US opinion polls, which indicated that the overwhelming majority of you want the withdrawal of the US forces from Iraq, but he objected to this desire and said that the withdrawal of troops would send a wrong message to the enemy."

"Operations are under preparation, and you will see them on your own ground once they are finished, God willing"

Osama bin Laden 

"[Bush said:] It is better to fight them on their ground than they fighting us on our ground.

In my response to these fallacies, I say: The war in Iraq is raging, and the operations in Afghanistan are on the rise in our favour, praise be to God."

Aljazeera dedicated its evening broadcast to Arab and Muslim analysts who gave their assessments and analysis of bin Laden's approach.

Shaikh Said bin Zughair, a prominent Saudi Muslim scholar, said bin Laden was delivering a professional political message.

"He was responsible. He said do not fight us and we will not fight you, then he offered a truce. He was speaking politically," he said. 

"It is not the first time that al-Qaeda offers a truce. The last time it offered it to European peoples. I remember back then, they asked a woman from London about her opinion of the suggested truce.

"She said let us go for it, if bin Laden is sincere, we will be winners, if not, we will not lose anything."

Zughair called on the US to adopt this theory, saying reason sometimes beats politics.

Dr Dia Rashwan, an Egyptian specialist in Islamic movements, said the bad quality of the tape indicates that bin Laden is far from his aide Dr Ayman al-Zawahiri.

"We saw al-Zawahiri's previous recordings were clear and professionally recorded, while today's Bin Laden tape is of bad sound quality, which indicates that the two men live in two different environments.

"Bin Laden was specific in the terminology he used, he used the word 'war' to describe the situation in Iraq, while he used the term "increasing operations" to describe the situation in Afghanistan."

US response

The White House said on Thursday that the US "does not negotiate with terrorists".

Bin Laden, who had not been heard of since an audio tape was made public on December 27, 2004 in which he anointed Abu Musab al-Zarqawi, Iraq's most wanted man, as al-Qaeda's leader in Iraq, also said his network was winning the war against the US.

"I would like to tell you that everything is going to our advantage and the number of your dead is increasing, according to Pentagon figures."

Al-Zawahiri said in videotape in September that his leader was still alive and leading the jihad against the West.