Vital documents remain secret

Tony Blair's long-awaited appearance at the Iraq inquiry looked set to be hampered last night after the Government refused to declassify crucial documents relating to his decision to take Britain to war.

The failure to release the papers led to calls yesterday for the inquiry to be suspended. While Sir John Chilcot's team have been handed all the documents, they are unable to quote from classified material and may have to restrict questioning.

Security around Westminster's QEII conference centre, where the inquiry is taking place – and at Mr Balir's central London home – will be beefed up today to combat protests planned for the appearance of Mr Blair. Negotiations between the police and protesters broke down yesterday, with the organisers of the demonstration told that they cannot gather on land outside the conference centre as it is private property. It is expected that the protesters will be directed to a street nearby.

The missing documents feature prominently in the questions that Mr Blair is expected to face. The inquiry team are planning to ask about a series of secret letters he sent to President Bush in 2002, apparently pledging that British troops would "be there" if military action became necessary.

Other key documents yet to be released include memos written by Mr Blair's foreign policy adviser, Sir David Manning. A draft of legal advice given to Mr Blair by his Attorney General, Lord Goldsmith, also remains classified. "If a short adjournment is necessary to ensure that this vital information is declassified, then this should be considered," said Ed Davey, the Foreign Affairs spokesman for the Liberal Democrats.

Downing Street said yesterday that the Prime Minister had not blocked the publication of the documents, insisting that he was determined to make the inquiry as open as possible. No 10 said Gordon Brown was powerless to intervene to have them released.