London police said on Thursday they had completed their probe into the "Partygate" scandal rocking Boris Johnson's government, issuing a final wave of fines but no more for the prime minister.

The Metropolitan Police said in a statement that of the fines issued for breaching Covid restrictions, 73 were to women and 53 to men but that some people received more than one fixed penalty notice.

Police were called in to investigate gatherings at Downing Street and across government departments on eight dates between May 2020 and April 2021. 

Last week, the force said it had issued more than 100 fines. 

The exact amount of the penalties has not been confirmed, but the fines can range from £30 to £10,000 (35-11,800 euros, $37-12,400) for the most serious breaches.

Those fined so far include Johnson, his wife Carrie and finance minister Rishi Sunak. Johnson's fine -- the first for a sitting British prime minister -- prompted calls for him to resign or be forced out. 

The government said they were fined for a gathering in Downing Street marking the prime minister's birthday in June 2020, but that he would not receive another fine.

Carrie Johnson, wife of the British Prime Minister, was also fined. Photo: AFP

'No further action'

'The Met has confirmed that they’re taking no further action with regards to the prime minister," Johnson's spokesman told journalists after the police announcement.

The conclusion of the police investigation, which the Met said cost £460,000 ($571,000, 543,000 euros), means that senior civil servant Sue Gray's long-awaited report into "Partygate" can now be published in full.

"Sue Gray will complete her work and then hand that over and then we will publish that as soon as possible," Johnson's spokesman said.

British media reported that that could happen next week.

In a partial release of her findings in January, she criticised "failures of leadership" at the top of government for allowing the parties to happen.

The leader of the main opposition Labour party, Keir Starmer, said the investigation had shown "industrial scale law-breaking in Downing Street", and repeated his call for Johnson to resign.

"What I want to see now is the full Sue Gray report published there are no further hiding places to the prime minister on that," said Starmer.

Starmer has himself promised to step down if police in northeast England fine him for his own alleged breach of coronavirus laws during a campaign meeting.

The gathering took place in Durham in April last year, with a video later emerging of Starmer drinking beer and eating a takeaway meal inside an office with party colleagues.

"There was no breach of the rules by me or anybody in my team," Starmer told Sky News. "I'm confident about that. And therefore there's no comparison to be made here."

Labour leader Keir Starmer has also faced questions. Photo: AFP

'They lied'

Londoner Safiah Ngah, whose father died of Covid, said the "nearly half a million pounds this investigation has cost could have been spent on support services for the bereaved".

"Instead it was spent investigating our own government and all because they lied and failed to acknowledge they had broken the law.

"Conservative MPs promised they would make their mind up about the Prime Minister when the Sue Gray report is released. There is no reason for that report to be delayed any longer," Ngah said, speaking on behalf of the Covid-19 Bereaved Families for Justice group.

"Every day they do not act they allow a man who gaslit us and lied to the faces of the bereaved when he claimed he did 'everything possible' to save our loved ones remain the highest office in the land."

The police probe was launched on January 25 and saw 12 detectives sift through 345 documents, including emails, door logs, diary entries and witness statements, 510 photographs and security camera footage and 204 questionnaires, the Met said.

"Our investigation was thorough and impartial and was completed as quickly as we could, given the amount of information that needed to be reviewed," said the Met's Acting Deputy Commissioner Helen Ball.

"This investigation is now complete."

Johnson has apologised for the breach of Covid regulations, but refused demands to resign after becoming the first UK leader to be found to have broken the law while in office.

Johnson also faces an investigation by a parliamentary committee into his past denials to the House of Commons of lockdown lawbreaking.

The parties have fuelled widespread public anger against the ruling Conservatives, who suffered a drubbing in recent local elections.