The Metropolitan Police has been urged to reopen its investigation into the Downing Street “Partygate” scandal following the release of a podcast that raised questions about the force’s initial inquiry.

The deputy chair of the London Assembly’s police and crime committee has written to the Met commissioner, Mark Rowley, asking if he was “taking new information into account when making a decision regarding the reopening of the investigation” into the Downing Street lockdown parties.

The revelations include allegations that Downing Street staff corroborated their stories before filling out the Met’s questionnaires into lockdown parties, and that Number 10 officials deliberately destroyed evidence of partying before the force and a separate Cabinet Office inquiry by Sue Gray could investigate.

Originating from an ITV investigation into Partygate, the findings also include allegations that Boris Johnson joked to Downing Street staff that “this is the most unsocially distanced party in the UK right now” while attending a leaving do at Number 10.

In his letter to Rowley, Unmesh Desai, deputy chair of the committee that scrutinises the mayor’s office for policing and crime, which in turn oversees the Met, states: “You will no doubt be aware of the new evidence that directly contradicts the former prime minister’s claim that he was not aware of any rule breaking at 10 Downing Street. There are also reports of evidence demonstrating rule breaking being destroyed by staffers.”

The Met closed its investigation into Downing Street parties last May after informing Johnson that he faced no further action other than a £50 fixed penalty notice that he had received the previous month for flouting Covid laws at his birthday party in Downing Street in June 2020.

In total the Met issued 126 fines to 83 people during its inquiry, for events on eight different dates.

Johnson is due to appear next month before parliament’s privileges committee, which is examining whether he misled MPs about law-breaking parties during the Covid pandemic.

In the letter Desai adds: “I have raised the apparent inconsistency in how the MPS [Metropolitan Police Service] have approached the investigation with your predecessors – particularly regarding why the former prime minister was issued with only one fixed penalty notice for his birthday party, but not for the other events, including the leaving drinks where there is photographic evidence of him holding a glass of champagne and making a toast.

“It has also been reported that the questionnaires sent by the police to those under investigation were easily navigated by staffers at 10 Downing Street, who were able to corroborate stories.”

The development follows reports last week that the government’s spending watchdog, the National Audit Office, is examining the contentious decision to provide £220,000 of taxpayers’ money to fund Johnson’s legal defence for the inquiry into his Partygate denials.

Last week it emerged that Johnson’s declared income since leaving office last September stands at almost £4.8m, including an advance payment of nearly £2.5m for speaking events.