IAN Blackford has called for the UK Parliament to force Boris Johnson to release the Sue Gray report into partygate in full.

The SNP Westminster leader said MPs had previously used parliamentary procedure to make public documents that the government didn't want to release.

Those related to Brexit, Blackford said, adding that similar powers could be exercised over the findings of the Gray inquiry.

The highly anticipated report by Gray - a senior civil servant in the Cabinet Office - was due to be released but publication appeared to be delayed when the Metropolitan Police announced an investigation into allegations of lockdown parties at Number 10.

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It then emerged that the Met - which had refused to hold an inquiry - when reports of gatherings first surfaced last year had decided they would investigate the matter.

But the force then told Gray her report should make "minimal reference" to any alleged incidents under police scrutiny meaning that if she agreed only redacted or limited findings from her probe could be published.

Asked on the BBC's Sunday Show about whether Parliament could force the Prime Minister to released the Gray report in full, Blackford said: "Yes, we can because in the end this is a report which Boris Johnson has promised the Parliament, so Parliament can use its power to compel the Government to release any information that it wants. 

"And my message to parliamentarians is we have to do our job. We need to have this report. The public are demanding it and there is no reason why it should be held up. So let's see what we can do under parliamentary procedures to see what we can do."

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He added: "I have to confess that in itself will take time. The best thing would be for Sue Gray to give it to the Prime Minister and the Prime Minister to take responsibility and publish it.

"And we hold the Prime Minister to account in Parliament tomorrow."

Blackford went on to say that MPs could put down motions in the Commons demanding the report be released.

"We've done this over government papers, over Brexit, for example," he said adding Westminster sees itself as "sovereign".

Blackford also told viewers that there was no legal reason why the Gray report should not be published rightaway and it did not have to be held back because of potential prejudice to the police investigation.

"Of course it should be done properly. We called for a police investigation right at the start of this and it didn't happen," the SNP MP said.

"When the police announced their investigation on Tuesday, it was said then that there was no reason why the report should be held up. Let me state that under sub judice rules there is no reason why this can't be published.

"We are talking about summary offences, we are not talking about jury trials. There is no reason why this should not be in the public domain." 

Meanwhile, Labour’s shadow levelling up secretary Lisa Nandy this morning called on the Prime Minister to “come clean” over claims of lockdown-busting parties held in Downing Street.

She told the BBC’s Sunday Morning show: “The reason that we’ve got to have the Sue Gray report is because the Prime Minister won’t come clean on what has been going on in Downing Street and his involvement in it.

“We could sort all of this out without him having to hide behind a civil servant or the Met Police, he could just come clean, but since he won’t come clean we believe that the most important thing is to get that report out in full.

“There are a lot of bereaved families, there are a lot people who made huge sacrifices who deserve to hear the truth from the Prime Minister and if he won’t put an end to this circus and this stasis in Government, when people are dealing with huge issues around the country, cost-of-living crisis, levelling-up plans stalled, if he won’t do it, then that report has to come out in full, so that people can judge for themselves.”

Earlier, Foreign Secretary Liz Truss, one of the frontrunners to replace Johnson if he is forced to resign, told the BBC that the PM is “absolutely” the best person to lead the Conservatives into the next general election.

Asked if she is tempted by the top job, she said: “There is no contest. There is no discussion.”

On whether Johnson is the best leader to take the Tories into the next general election, Truss said: “Absolutely he is.”

Asked when the report will be published, Truss said: "That's a matter for Sue Gray."

She added: "It is our intention to publish the full report.

"There are issues, of course, with the fcat that we now have the police investigation alongside the Sue Gray report - but we have an independent report being conducted by Sue Gray, we have an operationally-independent police force and we have to allow them to get on with that.

"My view is the Prime Minsiter has apologised for what happened. He made clear mistakes were made. We have so many other issues of major importance for this country to focus on."