The head of al-Jazeera is delivering a letter to Tony Blair demanding the facts on reports that President Bush suggested bombing the Arab TV station.
Al-Jazeera journalists stage a protest over the memo at their Qatar HQ
He wants a memo published which is alleged to show Tony Blair dissuaded President Bush from bombing its HQ.
Last week the Daily Mirror reported what it said was the contents of a memo showing Mr Blair had talked the US President out of the attack last year.
Wadah Khanfar is calling for the facts to be made public and urgent talks.
Attorney General Lord Goldsmith has warned newspaper editors against publication, citing the Official Secrets Act.
According to press reports, the memo includes a transcript record of Mr Blair attempting in April 2004 to persuade Mr Bush not to bomb al-Jazeera's HQ in Qatar.
Qatar is an ally of the US and was the location of US military headquarters during the Iraq war.
The White House dismissed reports of the conversation as "outlandish", but US officials have openly accused al-Jazeera of being a mouthpiece for al-Qaeda.
Speaking on BBC Radio 4's Today Programme, Mr Khanfar said: "Al- Jazeera is in the foremost of free form and democracy in the Arab world and therefore this news that we have heard is very concerning.
"So we demand a proper explanation and we would like to know the facts about this letter."
He said the matter was very important and that it concerned not only al-Jazeera but journalists across the world.
"We need to know if this discussion has taken place or not...if this document exists or not.
"By banning this document from being published it does cast a lot of concerns about this issue.
"When we are talking about bombing a TV station like that I think it is of historical value to know what's happened."
He said al-Jazeera had also asked the White House for an explanation.
Downing Street said on Friday that it was quite happy to talk to al-Jazeera as it was to other broadcasters.
Clarifying his position, Lord Goldsmith said he had not been seeking to gag newspapers and had instead been urging them to take legal advice.
"I am acting in my independent role, this is not the Government acting ... it is me acting in my independent role to protect the administration of justice, because there is a live case going on at the moment which mustn't be prejudiced, and secondly to protect the law."
Cabinet Office civil servant David Keogh has been charged under the Official Secrets Act of passing the memo to former Labour MP Tony Clarke's researcher Leo O'Connor.
Both men are due to appear at Bow Street Magistrates Court next week.
Last week Labour MP and former defence minister Peter Kilfoyle tabled a Commons motion calling for the memo to be made public.
He accused ministers of using the Official Secrets Act to save political embarrassment rather than protect national security as it is intended.
Lord Goldsmith also denied the Act was being used to prevent political embarrassment.
"It is not being used to save the embarrassment of a politician. That is completely not the case at all."
He also refused to confirm the contents of the memo.
BBC security correspondent Frank Gardner says this latest row follows a history of tension and mutual suspicion between al-Jazeera and the US administration.
Many of al-Jazeera's employees have long been privately convinced that their offices in Kabul and Baghdad were deliberately targeted by the Pentagon in 2001 and 2003 respectively.