An investigation into lockdown parties at Downing Street has reportedly been "blindsided" by new revelations of rule-breaking.
Sue Gray, a senior civil servant, is investigating claims of illegal gatherings at No10 on the orders of the prime minister.
But questions have been raised about whether her inquiry is getting the full story after The Times newspaper said her probe had been taken off guard by new claims.
The Independent reported this week that some officials have been asked to delete evidence of parties from their phones - a revelation which raised questions about the level of staff cooperation with the probe.
The investigating official is said to be concerned that Downing Street staff are withholding information about parties from her after.
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It comes after it was claimed on Friday that staff gathered after work for two events on April 16 2021 – the eve of the Duke of Edinburgh's funeral.
Staff filled a suitcase with bottles alcohol and danced in the basement of No10, with one special advisor DJing, it was alleged.
There were also further claims on Friday evening by the Daily Mirror newspaper that No10 regularly practiced "wine time Fridays" during the pandemic and even purchased a specialist fridge to store bottles.
Boris Johnson is reported to have regularly witnessed the gatherings and even encouraged staff to let their hair down.
Other claims include the fact that Boris Johnson was so unwilling to follow Covid-19 rules that a chair had to be propped against the door of his room to ensure he would self-isolate.
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"He kept coming out so we put two chairs across the door like some kind of puppygate," one figure told The Times.
The newspaper claims ministers believe Mr Johnson is in a "last-chance saloon" with the Conservative party – as the Tories tank in the polls.
Unless he resigns of his own accord the prime minister would have to be removed by his own party, with letters written to the chair of its backbench 1922 committee to trigger a leadership contest.
Recommended Boris Johnson ‘planning end to Plan B’ Covid restriction as he works to keep his job PM ‘unable to lead’ following party accusations, says Starmer Downing Street staff ‘held regular wine-time Friday’ drinks during lockdown
A No 10 spokesperson said: "There is an ongoing investigation to establish the facts around the nature of gatherings, including attendance, setting and the purpose with reference to adherence to the guidance at the time.
"The findings will be made public in due course."