The publication of the official report into the Iraq War could be delayed by more negotiations with the high-profile figures criticised.
The Chilcot Inquiry has announced it had finally secured the last responses to its first draft.
But its chairman also refused to set out a timetable for the report's publication, despite intense pressure from politicians and those who lost loved ones in the conflict.
Sir John Chilcot has promised ministers a deadline at the end of the so-called ‘Maxwellisation’ process.
The controversial system allows those named in the report to respond to its claims before publication.
The inquiry said that now that all the comments have been collected they had to be evaluated.
A source said that officials could still be forced to enter into discussions with those involved to seek clarification on their responses.
Sir John has faced criticism that the process has been unnecessarily drawn out.
When it was commissioned by then prime minister Gordon Brown in 2009 he said that he expected the inquiry to take "at least a year".
In a letter to the chairman of the House of Commons Foreign Affairs Committee, Sir John said that he had now received the last Maxwellisation response.
Further work was required to evaluate the "detailed and substantial" submissions, he said.
"As soon as I am able to, I will write to the Prime Minister with a timetable," he added.
Those who may come under fire in the report include former prime minister Tony Blair.
Sir John has been threatened with legal action from families of Iraq War casualties over his failure to set out a timetable.
David Cameron last month said he shared the families' "immense frustration" and urged the inquiry chairman to "get on with it".
However, Downing Street has always insisted that the timing of the report's publication is a matter for the independent inquiry.
Last night SNP defence spokesman Brendan O’Hara called for a "firm deadline".
He said: “The Chilcot Inquiry was demanded because people wanted answers, yet six years and £10 million later we still have nothing.
“It was overdue six years ago and the fact that there is still no report is completely unacceptable."
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