* Gray report on boozy Downing St parties due Wednesday
* Minister says PM Johnson already said sorry, been fined
* New evidence of lockdown parties has emerged this week
LONDON, May 25 (Reuters) - Boris Johnson's government went on the defensive on Wednesday, as it awaited an official report into coronavirus lockdown-breaking parties at the UK prime minister's Downing Street office and residence.
Senior civil servant Sue Gray's report is expected to be published on Wednesday, against a backdrop of new photographs and accounts this week of boozy gatherings that took place there.
It is set to offer more details of parties at the heart of power while the rest of the country was under a strict lockdown to try to curb the spread of COVID-19.
Johnson, who was fined by police for attending his birthday party during lockdown but escaped further penalties, has been forced to apologise for the culture in Downing Street, but more details may only add to pressure for him to quit.
Seeking to play down Gray's report, a British minister said police had investigated "all of these events".
"They've issued a fixed penalty notice to the prime minister in respect of one of those events that he that he attended. He's paid that penalty," Environment Minister George Eustice told Times Radio.
"He's apologised ... So I'm not sure that anything new will come from this report other than further detail, but of course, we will... look at it."
For months, evidence of alcohol-fuelled parties at Downing Street has dripped out into the media, forcing Johnson to apologise, change the team at his office and promise a reset to try to restore his authority.
But his actions have failed to stem a steady drumbeat of calls for his resignation, with some lawmakers saying his position is untenable if he lied to parliament, a matter under investigation by parliament's Committee of Privileges.
Ministers say he has not misled parliament.
Gray's report follows new revelations of what went on inside Downing Street when coronavirus rules meant people could not socialise outside their households or even, in many cases, attend funerals for loved ones.
Late on Tuesday, the BBC's Panorama programme cited insiders as saying staff crowded together at such events, and how, sometimes in the morning when arriving for work, they were met with bottles littering parts of the building. Some parties went on so late, they said, some people ended up staying all night.
On Monday, photographs published by broadcaster ITV appeared to show Johnson on Nov. 13, 2020 making a speech and raising a toast, with a glass in his hand, standing next to a table on top of which are several open wine bottles.
Johnson's spokesman did not address the photographs directly but said that, after the publication of the Gray report, the prime minister would address parliament and answer questions. (Reporting by Elizabeth Piper and William James; editing by John Stonestreet)