Boris Johnson is being put under pressure to explain a "secret" meeting he took with Sue Gray ahead of the release of her highly-anticpated report into the 'partygate' scandal.

It is understood the pair met at least once to give an update on the document’s progress while it was being drafted, but a Whitehall source said that its contents were not discussed at any point.

Although the exact nature of the talks remains unclear such meetings would not have been viewed as unusual, the source said, with the aim to take stock of what stage the report was at.

The BBC reported that the discussions touched on whether photos would be revealed to the public, and that Ms Gray initiated the meeting “to clarify her intentions” for what would happen once the police investigation concluded.

Bournemouth Echo: Boris Johnson was asked to explain what was said in his meeting with Sue Gray (PA)Boris Johnson was asked to explain what was said in his meeting with Sue Gray (PA)

But a spokesman for the Gray inquiry disputed this account of events.

They confirmed that a meeting took place, but told the PA news agency they would not characterise the talks in that way.

There has also been some confusion on who called the meeting in the first place, with Sky News reporting Sue Gray's spokesman saying that she didn't initiate it whilst Downing Street has said she did.

It comes as about 30 people, including Mr Johnson, are being contacted by the Cabinet Office to warn them of the contents of the document ahead of its publication.

Angela Rayner, Labour’s deputy leader, called on the Prime Minister to explain what had been discussed.

She said: “Boris Johnson must urgently explain why he held a secret meeting with Sue Gray to discuss her report despite claiming her investigation was completely independent.

“Public confidence in the process is already depleted, and people deserve to know the truth.

“This is a Prime Minister incapable of taking responsibility for the rotten culture he has created in Downing Street or of doing the decent thing.

“The Sue Gray report must be published in full and with all accompanying evidence.”

Liberal Democrat MP Christine Jardine also called on the PM to throw light on the meeting, saying that any notion of "a stitch-up" would make "an absolute mockery" of the report.