British police will recommend issuing the first 20 flat-fine notices for violating coronavirus lockdown rules at meetings at Prime Minister Boris Johnson's offices and residence, Scotland Yard said in a statement.

Police are investigating 12 gatherings held on Downing Street after an internal investigation found that Johnson's staff threw parties with alcohol and the prime minister himself attended several events.

"We will today initially begin to refer 20 fixed penalty notices to be issued for breaches of Covid-19 regulations," the Metropolitan Police said in a statement.

The fines would be issued by the ACRO Criminal Records Office.

"Boris Johnson’s Downing Street has been found guilty of breaking the law," said Angela Rayner, deputy leader of the opposition Labour Party.

"The culture is set from the very top. The buck stops with the Prime Minister, who spent months lying to the British public, which is why he has got to go."