Will Blair's most loyal aide be the fall guy for weapons debacle?

When Alastair Campbell was a political journalist, he admitted having an obsession with the intelligence services. After the Cold War ended, he often asked what MI5 and M16 officials actually did in their "fabulously expensive new offices". In 1993 he wrote: "I'll assume many do nothing but wait for a Labour government to undermine."

Mr Campbell may now feel his prophecy is coming true. Downing Street is increasingly irritated by the stream of leaks from anonymous security sources suggesting that Tony Blair's aides, including Mr Campbell, doctored intelligence reports to exaggerate the threat posed by Saddam Hussein's weapons of mass destruction (WMD) in the run-up to the Iraq war.

In a memo that surfaced at the weekend, John Scarlett, chairman of the Joint Intelligence Committee, told Mr Campbell that Mr Blair's "foreword" had been included in a WMD dossier published in September but that a hard-hitting conclusion had been "dropped". This was said to be a deal between Mr Campbell and security chiefs after months of bitter disagreement on what could be included in the dossier.

It was the second time that Mr Campbell had been at the heart of the storm over Iraq. Another report compiled by his staff, the so-called "dodgy dossier" issued in February, plagiarised an article written by a PhD student in California, and other parts were lifted from Jane's Intelligence Review.

Some Westminster observers are now wondering whether Mr Campbell, Downing Street's director of communications and strategy, may be the fall guy if no WMD are found in Iraq. With the Prime Minister unlikely to be toppled by the WMD row, his closest aide would certainly be a pretty good scalp for Mr Blair's critics.

During Mr Blair's week-long foreign trip, which ended yesterday, Mr Campbell avoided the journalists accompanying the Prime Minister for most of the time, in line with his decision in 2001 to step into a behind-the-scenes role and not brief political reporters.

The only time he spoke to the press came when he tried to "kill" a report on BBC Radio 4's Today programme that intelligence officials were unhappy with the September dossier's claim that Iraq could deploy some WMD within 45 minutes and had been ordered to "sex up" the document. In a rare on-the-record statement, during Mr Blair's visit to Saddam's former palace in Basra, Mr Campbell insisted: "This is totally false. There is nothing there that was not the work of the intelligence agencies." But his intervention failed to stem the WMD tide engulfing Mr Blair.

Yesterday Number 10 refused to comment on Mr Campbell's precise role in drawing up the dossiers. Asked if Mr Campbell felt under pressure, Godric Smith, the Prime Minister's official spokesman, replied: "No."

In theory, Mr Campbell could be vulnerable if Downing Street's communications team is criticised by Parliament's Intelligence and Security Committee, which is to investigate the WMD claims. In practice, this is unlikely. Government insiders believe that ministers would be more at risk if their widely reported public statements on Iraq's weapons were shown to be false or greatly exaggerated.

One minister said last night: "The idea that Campbell is under threat is ridiculous. People will try to target him because he is a big name. But he was doing his job, which is to hone the message to get the Government's case across. We couldn't put out a dossier written in the dry-as-dust language of the security services."

The latest row is bound to put the spotlight on the relationship between Mr Blair and Mr Campbell. There has been speculation that it cooled after the "Cheriegate" affair in December. Mr Campbell and his partner, Fiona Millar, who acts as Cherie Blair's media adviser, were both dismayed that Mrs Blair ignored their warnings about Carole Caplin, her lifestyle guru, whom they regard as a crank. It was Ms Caplin who introduced Mrs Blair to Peter Foster, the Australian conman who helped the Blairs to buy two flats in Bristol.

Ms Millar is expected to stand down from her post this summer, perhaps partly because of her frustration at Ms Caplin's increasing influence over Mrs Blair. Number 10 insiders insist that she is not "at war" with Ms Caplin or Mrs Blair and wants a job that lets her spend more time with her children. Her looming departure has inevitably sparked gossip that Mr Campbell might be heading for the exit door.

But that picture is not recognised by his friends, who insist he is as hard-working and committed as ever. One said: "You are bound to have your ups and downs, but nothing has really changed. His relationship with Blair is fundamentally as strong as ever."

Indeed, the pivotal role Mr Campbell played in the Iraq crisis - and more recently during the heated debate over the new European Union constitution - does not suggest he is on the way out.

Mr Campbell keeps a diary and ministers eye him nervously when he takes notes during cabinet meetings. One day, he will earn a fortune by writing a book on his time in Number 10 - and, after the current controversy, he may have more to say about the "spooks". But colleagues think he will "leave when Tony does". So the Campbell memoirs may still be some way off.

KEY PLAYERS IN THE SELLING OF THE WAR

JACK STRAW

The Foreign Secretary is assumed to have had a "good war", particularly in his performances at the UN Security Council. But as one of the most hardline backers of conflict he made repeated claims on the nature of the Iraqi threat.

Mr Straw said that Hans Blix and his UN team had provided "overwhelming" evidence that Iraq had WMD, citing his 173-page report published in February. But Dr Blix's report only ever referred to unanswered questions for Baghdad and stated that there was no evidence that the weapons still existed.

GEOFF HOON

The Secretary of State for Defence is another minister judged to have been a safe pair of hands in the war, and is one of the most hawkish members of the Cabinet.

As an essential member of the War Cabinet, he would have had access to the daily intelligence briefings and highly classified material that is supposed to have prompted Britain to go to war.

Mr Hoon repeatedly claimed that WMD would be found, but the MoD had a much smaller role than the Foreign Office in the overall effort to sell the conflict.

JOHN SCARLETT

The chairman of the Joint Intelligence Committee is a former MI6 officer who was forced this week to make a rare public statement to head off any suggestion that he would be made the scapegoat.

Mr Scarlett, who was MI6 station chief in Moscow, let it be known there was "no diversity or animosity" between the intelligence agencies and Downing Street and that while there was a "debate" over what should go into the dossier, ministers had the right to choose how to use it.