The 'Top Secret' memo leaked to the Daily Mirror in November 2005, under the headline "President Bush planned to bomb Arab TV station Al Jazeera", was purported to have recorded discussions between Tony Blair and George Bush in the Oval office in 2004 regarding the US attack on Falluja to drive out insurgents where many civilians were killed.
It claimed that at the meeting, Bush was dissuaded from the plan to attack Al Jazeera by Tony Blair, who said that an attack on Qatar, where Al Jazeera was based, would provoke a major backlash.
Sources told the Daily Mirror that Bush made it clear that he wanted to bomb Al Jazeera in Qatar and other locations, and denied reports that the threat was made in a humorous way.
Government communications officer, David Keogh, was found guilty of "making a damaging disclosure" and jailed for six months for passing on the secret memo.
Keogh was told by Judge Richard Aikens that his "reckless and irresponsible" actions could have cost British lives.
Keogh's co-accused, parliamentary researcher Leo O'Connor, was sentenced to three months in prison at the trial. Much of the trial was held behind closed doors with the press and the public banned from attending.
Keogh was accused of passing the memo to O'Connor in May 2004. At the time Blair said he had no information about any proposed US military action against Al Jazeera and the White House dismissed the claims as "outlandish and inconceivable".
Al Jazeera said it was continuing to seek clarification on the Daily Mirror report and reiterated its demand to see a copy of the relevant section of the memo.
The news broadcaster said it submitted a Freedom of Information application early in 2006 requesting the disclosure of the contents of the memo but the request was denied.
A spokesman for Al Jazeera said: "Any substantiation of the contents of the memo would be extremely serious not only for Al Jazeera but for media organisations across the world. It would cast significant doubts on the US administration's version of previous incidents involving Al Jazeera's journalists and offices."
During the invasion of Iraq, Al Jazeera's Kabul bureau and Iraq bureau were hit by the US forces resulting in the death of Al Jazeera journalist Tareq Ayoub. The US described both incidents as accidents.
Al Jazeera came to prominence in the Western world following the September 11 2001 terrorist attacks in the US. The network was favoured by Arab terrorist organisations such as Al Qaeda for releasing footage of Western hostages and messages from leaders including Osama bin Laden.
Earlier this week the channel was passed footage purporting to be of the press card of kidnapped BBC Middle East reporter Alan Johnston, who has now been missing for 60 days.
The network launched its English language channel in November.