Opposition MPs have demanded more details about the event, which took place some weeks ago and was made public last night by Sky News.

Sources initially claimed that Ms Gray initiated the meeting. But this morning but a spokesman for the Gray inquiry intervened to deny this, leading to a clarification by Number 10.

Downing Street sources issued a statement which said the meeting had not been ordered by the PM personally. There is no dispute the idea and suggestion for the meeting came from a Number 10 official.

Ms Gray's spokesman also disputed claims the pair talked about whether to include photographs.

The briefing war will deepen suspicions about the purpose of this the meeting, revealed days before the final report is due to be published.

Multiple sources agree that the PM and the top official discussed the progress of the Met Police inquiry and did not discuss the judgements she would come to in her final report.

However it is unclear why Mr Johnson needed to see Ms Gray personally if this was the sole extent of their chat.

Labour's deputy leader Angela Rayner called on the prime minister to "urgently explain" why the "secret meeting" had taken place.

She said public confidence in the process had already been "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," she added.

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

Read more: What is the Sue Gray report and what can we expect from the full findings?

Liberal Democrat MP Christine Jardine said: "Any whiff of a stitch-up would make an absolute mockery of the report."

On Thursday, the Metropolitan Police confirmed they had ended their investigation into lockdown-breaking parties in Downing Street and Whitehall, and had given out 126 fines for 83 people.

The conclusion of the police investigation cleared the way for Ms Gray's report into the parties to be published in full.

A source close to her team said the aim was to publish it as soon as possible, with next week likely.

Sky News understands discussions about whether or not to name senior civil servants who have been awarded fines are ongoing.

Mr Johnson also faces a parliamentary investigation into whether he misled the House of Commons about the parties.