'Dubbed a liar': Port to appeal Butters verdict

"The club believes strongly in Butters' account of events and will formally contest the verdict," the Power said in a statement on Wednesday night.

A date for the hearing has yet to be set.

Power chairman David Koch earlier said the club and Butters were irate at the guilty verdict.

"He (Butters) is incredibly angry with the outcome. He quite rightly believes he's been dubbed a liar," Koch told Adelaide radio station 5AA.

Butters, charged with using abusive and insulting language towards field umpire Nick Foot, was fined $1500 by the tribunal.

The tribunal was "satisfied to the requisite standard" Butters had made the offending comment.

"It is implausible that Mr Foot would invent the offending comment," the tribunal's judgment said.

"It was put to him that there were several distractions and that he had misheard what Mr Butters said. We also consider that to be implausible."

Complicating the matter, the entire verbal exchange was not picked up by Foot's microphone - though some comments before and after were.

"There are many possible reasons for that, including the positioning of players to the microphone," the tribunal said.

The tribunal sided with Foot, who alleged Butters said "How much are they paying you?" after he awarded a free kick to St Kilda in Port's 14-point loss on Sunday night.

Butters vehemently denied that comment, insisting he said: "Surely that's not a free kick."

AFLPA chief executive James Gallagher was disappointed by the outcome.

"A misunderstanding about what was said on field should have been resolved in the aftermath of the match, not referred to the tribunal," Gallagher said in a statement.

"The tribunal determining not to accept all of the evidence consistent with Zak's version of events ... nor have sufficient doubt when upholding a charge is deeply concerning."

But AFL Umpires Association chief executive Rob Kerr defended Foot.

"Nick Foot has never wavered from his account," Kerr said in a statement.

"His response to what he perceived was said was entirely consistent with the expectations placed on umpires charged with protecting the game's integrity.

"And he has behaved appropriately through each step of this process at the cost of significant personal discomfort, particularly with some of the online vitriol."

The flashpoint came when Foot paid a free kick to St Kilda's Mitch Owens, prompting Port's Ollie Wines and Butters to protest.

"The comment that Butters made to me was 'How much are they paying you?'" Foot told the tribunal.

"It questioned my integrity. I'm 100 per cent adamant that those are the words Zak Butters said to me."

But Butters said he was "100 per cent sure" he did not make that remark.

Essendon coach Brad Scott was among AFL identities to express unease with the case.

"I'm probably like every footy fan and person waiting for an explanation about how you can take one person's word over another ... how you form a conclusion based on that is totally beyond me," Scott told reporters.