Tony Blair letters to George Bush wiped from the records

Tony Blair's private letters to George Bush on Iraq were considered so sensitive they were expunged from the official Whitehall record, it has emerged.

Evidence released by the Iraq Inquiry yesterday shows that No 10 officials drew up two accounts of the then prime minister's dealings with the United States president - with all references to their correspondence being removed from the version for general circulation.

Inquiry chairman Sir John Chilcot on Tuesday expressed his frustration that Cabinet Secretary Sir Gus O'Donnell had refused to clear even limited extracts from the letters for publication by the inquiry.

The assurances which Mr Blair gave to Mr Bush regarding his support for US military action against Iraq are expected to form a key element of the questioning when the former prime minister appears before the inquiry for a second time tomorrow.

The inquiry yesterday released the transcript of a closed evidence session with Mr Blair's then private secretary Matthew Rycroft, who said he prepared twin accounts of conversations between Mr Blair and Mr Bush on a number of occasions.

Mr Rycroft said Mr Blair had always been clear that Britain would be with the US in any military action against Iraq. He described American policy on the issue as a "juggernaut".

"Even if the prime minister had wanted to push the juggernaut in a completely different direction, I suspect he would not have been able to and he didn't want to turn it around anyway," Mr Ryecroft said.

"The prime minister's view was that in this scenario, if we had collectively gone down the UN route and it had led to clear evidence of further material breach of Saddam's, therefore if we had our legal base, then in terms of policy - politics - the UK would be with the US in any military action."

The inquiry was adjourned until tomorrow.