LONDON (Reuters) -British police said on Thursday they had now made more than 100 referrals for fines as part of their investigation into lockdown rule-breaking at gatherings held in Downing Street during the COVID-19 pandemic.

British Prime Minister Boris Johnson apologised for receiving a fine in April for breaking lockdown rules by attending a gathering in his office to celebrate his birthday, but has refused to resign over it.

He could receive further fines for other gatherings, but on Thursday Johnson’s spokesman said the prime minister had not received another fine.

“As of Thursday 12 May, Operation Hillman, the investigation into breaches of COVID-19 regulations in Whitehall and Downing Street, has made more than 100 referrals for fixed penalty notices (FPNs) to the ACRO Criminal Records Office,” a police statement said.

Police said the investigation remained live, so the running total of fines could rise further.

It was the first update from the police on the number of fines issued in a month after they delayed them until after local elections, which were held last week.

In the last update on April 12, police said they had made more than 50 referrals for fines.

Police are investigating 12 gatherings held at Downing Street and the Cabinet Office after an internal inquiry found Johnson’s staff had staged alcohol-fuelled parties, with the British leader attending a few of the events himself.

The revelations have sparked calls for Johnson to resign, especially from the opposition Labour party. Johnson has said he did not realise he was breaking the rules but he had accepted and paid the police fine.

“The Prime Minister is clear there were things we did not get right, both in terms of what happened and then how it was handled subsequently,” Johnson’s spokesman told reporters.

Johnson’s governing Conservatives have attempted to turn the tables on Labour leader Keir Starmer, who is himself now subject to a police investigation.

Starmer has insisted no rules were broken during an event in April 2021 where he was pictured eating and drinking with colleagues while working into the evening, and has said he would resign if police issue him with a fine.

Pollster YouGov said the investigation had not impacted Starmer’s reputation negatively, with voters seeing him as the better choice to lead the country and 41% viewing him as principled, with only 23% seeing him as unprincipled.

That compares with much worse ratings for Johnson, with just 14% saying the prime minister is principled, compared with 65% who see him as unprincipled.

(Reporting by William James, Muvija M, Alistair Smout and Elizabeth Piper; Editing by Alex Richardson)