Dr Kelly's funeral is on 6 August
The Ministry of Defence has denied newspaper suggestions that it sought to destroy a document relating to Dr David Kelly.
According to the Daily Telegraph, officials were preparing to incinerate a "media plan" about the government weapons expert when they were stopped by security guards.
It is alleged that three days after Dr Kelly was found dead, the document was placed in a sack of material due to be burnt. The guards became aware of this and alerted the police.
On Saturday, MoD sources conceded to the BBC there had been a "security breach" on 20 July when a bag of confidential material due for incineration was left out overnight.
However the sources said they were not aware that any of the material in the bag, which was taken away by Thames Valley Police, related to Dr Kelly.
The BBC's political correspondent Norman Smith said it seemed unavoidable that Lord Hutton, who is carrying out an inquiry into Dr Kelly's death, would want to know if the police still have the bag and if so whether it does contain any relevant material.
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He said the allegation raises the spectre of a potential cover-up by government officials whose evidence is likely to form a key part of the inquiry.
Lord Hutton opened the inquiry on Friday, setting out its parameters and indicating that he would call the prime minister, Defence Secretary Geoff Hoon and BBC journalist Andrew Gilligan to give evidence.
Other witnesses would include Dr Kelly's widow, Janice, MoD officials, the BBC Chairman Gavyn Davies and the chair of the Foreign Affairs Select Committee, Donald Anderson.
The inquiry has been adjourned until 11 August, to avoid clashing with the scientist's funeral next Wednesday.
Dr Kelly was found dead in woods near his Oxfordshire home on 18 July, having apparently committed suicide by slitting his wrist.
Three days earlier, he had given evidence to the Foreign Affairs Select Committee after being named as the source for a BBC report that a government dossier on Iraq's weapons of mass destruction had been "sexed up".