Tony Blair's secret links to Gulf oil giants were revealed today as fresh details emerged of his "carte blanche" support for George Bush's Iraq war.

The former prime minister has been in the pay of the Kuwaiti government and a South Korean oil firm for up to 18 months, a parliamentary watchdog has revealed.

But the Advisory Committee on Business Appointments allowed Mr Blair to keep his contracts secret because of "market sensitivities" and because the Kuwaitis requested confidentiality.

In a further revelation, a classified memo from Mr Blair to President Bush showed the full extent of his support for the toppling of Saddam Hussein.

The personal note — which has been seen by the Chilcot Inquiry but not released by the Government — shows that Mr Blair wrote: "You know, George, whatever you decide to do, I'm with you."

The contents of the memo, which is buried in Andrew Rawnsley's book The End Of The Party, confirm the exact words Mr Blair used to offer his strong backing for Bush in July 2002, eight months before the invasion.

The Chilcot committee was barred from quizzing Mr Blair publicly about the private notes to the US president when he gave evidence in January. Downing Street has refused permission to release the secret documents.

Rawnsley's book shows that Sir Christopher Meyer, Britain's ambassador to the US, reacted with astonishment when he saw the note.

He phoned Mr Blair's foreign policy adviser Sir David Manning, saying: "Why in God's name has he said that again?"

Sir David replied: "We tried to stop him... but he wouldn't listen."