It has all the intrigue of the greatest political crisis in modern American history: the anonymous “Deep Throat” briefings to journalists, the accusations of a coverup — and even a leader who sweats in front of the television cameras.

Three decades on from the crisis faced by Richard Nixon, the British prime minister is embroiled in a scandal which, as one Labour backbencher put it, may be “more serious than Watergate”.

The allegations that Downing Street embellished raw intelligence material in order to legalise the invasion of Iraq simply will not go away. Tony Blair has been accused by two former cabinet ministers of “duping” colleagues over Iraq’s weapons of mass destruction (WMD) and of making a “monumental blunder” over the war.

Iain Duncan Smith, the Tory leader, told the prime minister last week that “no one believes a word you say”.

As with Watergate, Blair is not being pilloried for his central action — in his case helping to rid Iraq of its evil dictator — but for allegedly trying to mislead colleagues and the public. For a politician who has built his whole reputation on being a church-going beacon of integrity, this could not be more serious.

Far from being “a pretty straight kind of guy”, Blair is in some eyes beginning to resemble Comical Ali, the former Iraqi information minister Saeed al-Sahaf, who was infamous for making statements that defied reality.

This weekend, on the eve of the long-delayed announcement about membership of the eurozone — and only days away from an important cabinet reshuffle — Blair may feel the political agenda has moved on and he has survived one of the toughest crises of his premiership. But has he?

THE pressure on Blair was clearly visible at a news conference at the G8 summit last Monday. “It’s hot in here — just as well we’re in Evian, with lots of water,” he said as beads of sweat appeared on his forehead.

Blair’s six-day trip, including his “victory tour” of Kuwait and Iraq, had been sidetracked by leaks from intelligence sources claiming that Downing Street had “sexed up” their assessments in its dossier on Iraqi WMD published last September.

Clare Short, the former international development secretary, had also challenged the dramatic claim that Iraqi forces could launch WMD within 45 minutes of receiving the order from Saddam Hussein, which was at the core of Blair’s argument for going to war. And Robin Cook, the former foreign secretary, suggested the government had made a “monumental blunder”.

On the flight home from Geneva on Tuesday — over bacon, eggs, coffee and the headlines from the British newspapers — Blair began honing the fight-back. Sitting with him in the first-class cabin were three of his key aides, Sir David Manning, his foreign policy adviser, Matthew Rycroft, his private secretary, and Tom Kelly, his official spokesman.

Alastair Campbell, already back at No 10 planning the rebuttal, was in constant touch over the satellite phone.

They discussed the options available. A full judicial inquiry, as some were calling for, would give too much credence to the allegations, they agreed. Far preferable to order a private investigation by the intelligence and security committee of MPs reporting directly to the prime minister. Blair had already had a request from the committee on his desk for nearly a month. He decided to say yes.

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