Although the Deputy Prime Minister said there would be “full transparency”, he refused to confirm that the probe’s findings would be published in its entirety.

Asked if the public will be permitted to see the report in totality, Mr Raab told the BBC’s Sunday Morning programme: “The process for it will be for the Prime Minister to decide. I think the substance of the findings, there will be full transparency, and indeed he has said he will come back to the House of Commons and make a statement so there will be full scrutiny.”

When pressed on whether the report will be published in full, Mr Raab said: “I’m not quite sure the shape and form it will come, but the PM has been clear there will be full transparency around this so that people can see.”

Mr Raab insisted Tory MPs were rallying behind Mr Johnson, although he acknowledged the Prime Minister would have to resign if he was found to have misled Parliament.

“The code of conduct for ministers is very clear that if you mislead Parliament it is a resigning matter,” he told the BBC’s programme.

Last week, Tory MPs raised concerns that Ms Gray’s report could be redacted, prompting calls for all senior figures referenced in the inquiry to be named. However, Number 10 has previously insisted that the report will be published in full.

Angela Rayner, Labour’s deputy leader, stressed that “all accompanying evidence” must be disclosed after Ms Gray presents her report to the prime minister.

She said: “Boris Johnson cannot be allowed to cover up or obscure any of the truth when he has insisted on a hugely protracted internal probe to tell him which parties he attended and what happened in his own home.”