The Metropolitan Police’s decision not to issue any further updates on partygate fines until after May’s local elections has drawn criticism, with a human rights barrister saying that withholding information could influence the vote.

Downing Street has indicated it will still say whether the Prime Minister, who was already handed one fixed-penalty notice by police over a birthday event in 2020, receives further fines, despite Scotland Yard’s pause on announcements.

A Met spokesman said: “While the investigation will continue during the pre-election period, due to the restrictions around communicating before the May local elections we will not provide further updates until after 5 May.”

But Adam Wagner, an expert on Covid-19 regulations who has been involved in a legal challenge to the Met’s initial refusal to investigate lockdown-busting Downing Street parties, questioned whether the police should observe pre-election period rules which typically place limits on Government publicity around elections.

In a Twitter thread Mr Wagner wrote: “Maybe I’m missing something – the Met claim there are ‘restrictions around communicating before the May local elections’.

“Obviously there are for public officials but what are they in relation to the police?”

He pointed to the National Police Chiefs’ Council’s (NPCC) guidance on conduct during the pre-election period, which states: “Police business does not cease in a pre-election period and normal functions of policing must be performed.

“But particular care must be taken in this period to avoid activity or publicity that could, or reasonably be seen to, affect or influence the outcome of the election”.

Another clause of the NPCC guidance warns that “delaying an announcement could itself influence the political outcome or impede operational effectiveness.”

Mr Wagner wrote: “To be fair to the Met, I can see why, reading NPCC guidance as a whole, they might thing ‘ooh we shouldn’t be releasing information’ which could influence the election.

“But they are missing the point that deciding not to release information will itself influence the election”.

He also pointed out that the Met would not be releasing the name of any politician, just stating that a fine has been issued, as per the force’s policy so far.

Mr Wagner said that the police “should not care less what the potential political implications of their investigation are”, but instead “treat it like any other criminal investigation and work at the pace convenient to them”.

“If, for example, they believe the Prime Minister has committed more crimes and are waiting until after the local elections to say so, that is itself political interference – whereas taking their own pace is not,” he wrote.

Meanwhile, Downing Street indicated that it will still say whether Boris Johnson or the Cabinet Secretary are fined over partygate before the local elections, despite the police pause on issuing updates.

A No 10 spokesman said: “We’ve committed before to being transparent and to letting people know if that were the case. That hasn’t changed. But specifically the announcement made today – it’s clearly a matter for the Met Police, it’s their investigation and it’s an independent matter for them.”

He said that he was not aware of any conversations between Downing Street and Scotland Yard preceding Thursday’s announcement.