Image copyright PA Image caption Sir Jeremy Heywood has the final say over classified documents

The UK's top civil servant should no longer have responsibility for deciding which documents sought by the Iraq Inquiry should be declassified, a former foreign secretary has said.

Lord Owen said Sir Jeremy Heywood should not be the final "arbiter" because he worked closely with Tony Blair ahead of the 2003 invasion.

The Lord Chancellor should decide on behalf of the government, he added.

The inquiry, which began in 2009, has stalled over access to key material.

The inquiry had hoped to begin the task of writing to those likely to be criticised in its final report to give them the opportunity to respond - a prelude to possible publication in 2014 - but this process has been delayed.

Its chairman Sir John Chilcot has said the next phase of its work was "dependent on the satisfactory completion of discussions between the inquiry and the government on disclosure of material that the inquiry wishes to include in its report or publish alongside it".

Stalled

In a letter to the prime minister last week, Sir John acknowledged progress had been made but expressed his frustration that no agreement had yet been reached on the "more difficult" categories of document.

I cannot believe that, now as cabinet secretary, he can be the arbiter as to whether documents should be published between Sir John Chilcot and Tony Blair Lord Owen

The documents at issue include cabinet-level discussions in the run-up to the war, 25 notes from Mr Blair to President Bush and more than 130 records of conversations involving either or all of Mr Blair, Gordon Brown and President Bush.

Lord Owen, the former Labour minister and SDP leader who now sits as a crossbench peer, said it was "obvious there are differences of opinion" between the inquiry and the government over the scope of documents to be released.

In a letter to Prime Minister David Cameron, he said: "Sir Jeremy Heywood was principal private secretary to Tony Blair in No 10 from 1999 to 2003, the very time when the decisions to go to war were being taken.

"I cannot believe that, now as cabinet secretary, he can be the arbiter as to whether documents should be published between Sir John Chilcot and Tony Blair."

Lord Owen suggested that Sir Jeremy, who succeeded Sir Gus O'Donnell as the UK's most senior civil servant in 2012, was "not the government" and elected politicians should intervene.

He added: "I suggest you ask the Lord Chancellor (Chris Grayling) to form a judgement on behalf of the government as to what papers can be released," pointing out he already did so for secret material released under the 30-year rule.

'Step back'

Lord Owen's call is being backed by former Lib Dem leader Sir Menzies Campbell, who said the inquiry's work was being "thwarted" and it was "time to break the logjam".

"I do not doubt Sir Jeremy Heywood's scruples for one moment," he told the BBC. "But on the face of it he is someone who was inevitably close to some of the events into which Chilcot is investigating.

Image copyright PA Image caption The inquiry, led by Sir John Chilcot, has been running for nearly four years

"And it would obviously be sensible for him to step back in this case."

He added: "In view of the sensitive nature of these issues, it is essential that Parliament and the public are satisfied that the issues are being considered in a wholly objective and impartial way."

David Cameron has said de-classification requests must be handled "sensitively and carefully" but that he hopes a decision about the final sets of papers can be reached as soon as possible.

The Cabinet Office said that under the terms of the inquiry's protocols, it was decided that the cabinet secretary should be the "final arbiter" on what documents should be declassified.

"That remains unchanged and has the prime minister and deputy prime minister's full support," a spokesperson said.

"At the outset the government assured the inquiry of its full cooperation and it continues to do so."

The inquiry, which is examining the background to the UK's involvement in the invasion and its aftermath, has never set a firm deadline for publishing its final report - set to be about a million words long.

However, it was initially expected to be published in 2012.