Invercargill Mayor Nobby Clark's actions at a private event left an MC so upset she wished the ground would “open up and swallow her”, an investigation report claims.

On March 16, Clark attended a United Fire Brigades’ Association (UFBA) prize giving dinner as a guest of honour, alongside his partner.

But the mayor’s presence as a VIP soured, according to UFBA chief executive William Butzbach's letter of complaint to the council.

Clark has since apologised, saying he was suffering from “brain fade” following open heart surgery. He also maintained some of his behaviour was not as described.

Butzbach’s letter — dated 28 March — was made public on Tuesday afternoon, and forms the basis of a second code of conduct complaint against Clark.

In it, Butzbach wrote he was informed by several reliable sources that Clark had “articulated some disturbing and offensive views” at the event.

Some of the comments were made during a speech on stage and included a description of volunteer firefighters as second-class citizens and personal attacks on the MC, the complaint alleges.

In relation to the latter, the complaint claims Clark attacked the MC's appearance, competence as a communications professional, and made an untrue allegation she was having an affair with the association’s president.

Butzbach also alleged the mayor disparaged young people in positions of authority.

“All in attendance were horrified and appalled by the mayor’s hateful and disrespectful rhetoric,” Butzbach wrote in the complaint.

“Many of our members and guests left the room in disgust at this behaviour from the mayor.

“This has proven traumatic for my staff whereby we are providing professional support services to them.”

The investigation report further detailed the impact of the episode on the MC, saying she found Clark’s comments “deeply humiliating” and had been reduced to tears.

Days later, she was left anxious thinking about hosting another event, the report said.

The UFBA president — who was present at the event — said he leaned close to Clark following his speech and remonstrated with him. He claimed Clark did not reply and left the room with his partner soon after.

All interviewees agreed the mayor did not speak from notes and did not congratulate the competition winners.

Clark’s partner provided an alternative view of events, saying although the mayor had caused offence, he had not intended to make anyone uncomfortable.

She said the mayor’s sense of humour was “unique”, and was aggrieved by the criticism he’d drawn at the event.

Meanwhile, Clark said he was approached by a volunteer as he left the venue and told he was “on the mark” with his comments, while being asked to give the team a wave — which he did.

Although Clark acknowledged in the report some of his comments were “inappropriate” and showed immediate willingness to apologise, he maintained his overall conduct was not as described.

Earlier, Clark also indicated he would not assist with the investigation into his actions.

A letter from Wellington lawyer Dentons Kensington Swan to Invercargill City Council dated May 12 said the mayor had raised the question of scope for the council’s code of conduct as a reason for not cooperating with an investigation.

As a result of the investigation, Clark was found to be in breach of the council’s code of conduct, with the matter to be considered by the council at an extraordinary meeting on Friday.

Clark declined to make any comment ahead of that date.

A second code of conduct brought against the mayor in April is still being investigated.

It relates to his appearance on satirical news show New Zealand Today, which saw him repeat a racial slur he had previously drawn criticism for using.

LDR is local body journalism co-funded by RNZ and NZ On Air