Harry Brook will retain the captaincy of England’s white-ball team for next month’s T20 World Cup, despite receiving a final warning for his off-field conduct following an altercation with a nightclub bouncer in Wellington the night before a one-day international against New Zealand last November.

The Yorkshire batter, who was also made vice-captain of the Test side earlier this year as part of an attempt to prepare him to succeed Ben Stokes, issued a public apology for his embarrassing behaviour within hours of yesterday’s five-wicket loss to Australia in Sydney, which condemned England to a 4-1 series defeat.

The scuffle with a bouncer in Wellington, which was first reported by the Daily Telegraph, took place on 31 October after Brook was denied entry to a nightclub. The 26-year-old captained the side in the third one-day international the following day, scoring six from 11 balls, as England lost by two wickets to seal a 3-0 series defeat.

Brook is understood to have self-reported the incident to England’s management, which led to the England and Wales Cricket Board (ECB) launching a formal disciplinary process that culminated in him being fined £30,000, the biggest financial penalty available, and warned as to his future conduct. The Guardian has been told that the matter was handled by the highest levels of the ECB executive, who gave serious consideration to withdrawing the one-day captaincy.

“I want to apologise for my actions,” Brook said in a statement yesterday. “I fully accept that my behaviour was wrong and brought embarrassment to both myself and the England team.

“Representing England is the greatest honour of all, which I take seriously and I am deeply sorry for letting down my teammates, coaches and supporters. I have reflected on the lessons it has taught me about responsibility, professionalism and the standards expected of those representing your country.

“I am determined to learn from this mistake and to rebuild trust through my future actions, both on and off the field. I apologise unreservedly and will work hard to ensure this does not happen again.”

“We are aware of this incident and it has been dealt with through a formal and confidential ECB disciplinary process,” the ECB added. “The player involved has apologised and acknowledged their conduct fell below expectations on this occasion.”

Brook’s behaviour will lead to further scrutiny of England’s professionalism during two disastrous winter tours that have brought only one scrappy win in the two-day Melbourne Test from eight matches across two formats.

The ECB may also face questions about the nature of the disciplinary process. Earlier in the tour, managing director Rob Key had brushed off questions about social media footage that purported to show Brook and Jacob Bethell drinking at a rooftop bar in Wellington – earlier on the same night that culminated in the bouncer contretemps.

“There wasn’t any action, like formal action,” Key said, when asked about the footage of Brook and Bethell before the fourth Test in Melbourne. “We’ve had four years where we’ve had none of these issues really, with any of the players. And there’s a whole process that we put in place for stuff like that, for what you do if they’re out of line. And I didn’t feel like that was worthy of formal warnings. But it was probably worthy of informal ones.

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“I think that was a bit of a wake-up call actually for what they’re going into,” Key added. “I don’t mind players having a glass of wine over dinner. Anything more than that, I think is ridiculous, really.”

Key and the ECB also opted to take no action following an informal investigation into reports of excessive drinking during England’s mid-Ashes break in Noosa. Social media footage emerged from that trip of opening batsman Ben Duckett appearing to slur his words in a late-night exchange with fans, one of whom advised him to “get an Uber to the nets” due to his poor form during the series.

Brook was one of several England players photographed relaxing at a beachfront bar during the day in the Queensland resort. During a press conference before the third Test in Adelaide, he said the tourists “had a belting time” on the Sunshine Coast.

Although he was England’s second-highest run-scorer in the Ashes series after Joe Root, Brook did not live up to his billing in Australia, only passing 50 twice in 10 innings and not scoring a hundred.

In announcing a post-tour review shortly after the end of the Sydney Test, the ECB chief executive, Richard Gould, confirmed that its remit would include the team’s culture and behaviours, as well as on-field performance.