By Mike Wooldridge BBC world affairs correspondent

The Americans are suggesting that the latest "Osama Bin Laden tape" helps to prove their case that there are links between the al-Qaeda network and Iraq.

Baghdad has consistently denied that it has any links with al-Qaeda

The Iraqis say the Americans are simply searching for a new pretext for war.

Osama Bin Laden's main purpose - if it is his voice on the tape - seems to be to support ordinary Iraqi Muslims and to urge other Muslims to do the same.

But it is hard to draw a clear conclusion about whether there has been any shift in Bin Laden's long-standing antipathy towards Iraqi President Saddam Hussein and his secular, socialist regime.

The White House has said that at best the tape shows Bin Laden "making common cause with a brutal dictator" - and at worst that they now have a "burgeoning alliance".

Pragmatic liaison

The speaker on the tape does say that under current circumstances "there is nothing wrong in Muslim interests converging with those of the socialists in the battle against the Crusaders, even if we believe and declare that the socialists are apostates".

The US says al-Qaeda and Iraq have worked together

But whatever pragmatic liaison that may imply in the face of the threats of war against Iraq, the voice on the tape shows no particular support for Saddam Hussein as an individual and no concern about whether he stays in power.

"This Crusader war", it says, "concerns all Muslims whether the socialist party or Saddam remain in power or not".

US 'desperate'

Baghdad has consistently denied that it has any links with al-Qaeda, and the emergence of the tape has not made any obvious difference to Iraq's stand.

The head of an Iraqi parliamentary committee on international affairs, Salem al-Qubaissi, called it a "desperate bid by the US administration to establish a connection between Iraq and al-Qaeda" and part of a policy to find an excuse to launch an offensive against Iraq.

He claimed that the United States had mobilised the full range of its security services to find a link between Iraq and al-Qaeda but they had failed to come up with the evidence.

Suicide call

But, whatever the truth of the tape and its authenticity or otherwise, what Baghdad will find hard to ignore is that it has the capacity to play into the hands of public opinion in the United States and maybe elsewhere.

And included in the tape's rhetoric is a reference to suicide attacks.

It speaks of "the importance of martyrdom".

None of this is likely to dissuade those in Washington who see a growing, rather than diminishing, justification for war against Iraq.

Still alive?

There is clearly a gulf between a videotape and firm evidence to support the idea that Osama Bin Laden and Saddam Hussein may now have overcome their mutual distrust and be collaborating with one another.

And this tape, like its predecessors, is already being interpreted many different ways.

But if it is Bin Laden, it is more proof that he survived the war in Afghanistan.

And that is chilling enough for most Americans.