One of the world's biggest mining equipment suppliers has described a typographical error in an enterprise agreement that would have represented thousands of extra dollars in workers' pockets as an "honest mistake".

Key points: Komatsu Australia is fined in the Industrial Magistrates Court over breaches of the Fair Work Act

Komatsu Australia is fined in the Industrial Magistrates Court over breaches of the Fair Work Act The company blames a "typo" in the enterprise agreement covering workers at Kalgoorlie-Boulder's Super Pit gold mine

The company blames a "typo" in the enterprise agreement covering workers at Kalgoorlie-Boulder's Super Pit gold mine Union says Komatsu is "clutching at straws" and accuses it of gouging workers' pay

Japanese multinational Komatsu employs more than 3,400 people across its Oceania business.

Its Australian subsidiary has been fined $12,600 in the Industrial Magistrates Court in Perth for breaching the Fair Work Act.

Komatsu Australia's human resources manager, Grant Morgan, was also fined $2,500.

The breach related to an enterprise agreement covering employees at Kalgoorlie-Boulder's Super Pit gold mine, where Komatsu maintains a fleet of trucks, loaders and PC8000 shovels.

Komatsu's gigantic PC8000 shovels operate in the Super Pit. ( ABC News: Jarrod Lucas )

The contract includes a clause in which workers receive an annual bonus for meeting key performance indicators (KPIs), most of which are related to safety.

Instead of the agreed-upon 2 per cent bonus, Komatsu's official paperwork lodged with the Fair Work Commission incorrectly said workers would be entitled to a 10 per cent bonus.

Phillip Southgate, who has been employed by Komatsu as a shift mechanic since May 2010, took legal action via the Australian Manufacturing Workers' Union (AMWU).

The court heard Mr Southgate was paid $11,132.73 plus pre-judgment interest.

Company owns up to 'honest mistake'

Komatsu Australia's general manager of people and strategy, Colin Shaw, said the "typo" occurred when the agreement was renegotiated in 2017.

He said a standard-practice memorandum of understanding was subsequently signed with the bargaining representatives to acknowledge the "honest mistake".

"There's no point in appealing it [the court decision] because to us it was a legitimate mistake on the typo," Mr Shaw said.

"I think it's a good learning exercise for us, and for anyone, to double-check these agreements which get submitted, because a small typo can come back to haunt you."

The Super Pit is one of Australia's biggest-producing gold mines and has been operating since 1989. ( ABC News: Jarrod Lucas )

Komatsu has 17 people working under the enterprise agreement at the Super Pit, one of Australia's biggest gold mines and employer of about 1,100 workers and contractors.

The agreement is due to expire in December 2020.

Culpability lessened by 'typo'

The court heard Komatsu's regional service manager, Richard Edmiston, emailed Mr Morgan on April 27, 2017, drawing his attention to the mistake.

On May 1, 2017, Mr Morgan and the two bargaining representatives, Ian Yates and Edward Lettabelle, signed a memorandum of understanding to address the error.

But Magistrate Martin Flynn said the extent the company relied upon the memorandum "could hardly have been said to be reasonable", pointing out the document itself noted it did not have the legal effect of amending the approved agreement.

The court heard the error was introduced by the industrial consultant who drafted the document.

"It's noted that the person who drafted the proposed employment agreement document was not called by the company to give evidence," Mr Flynn said.

"And the point is made that it is surprising that the company did not, itself, independently check the contents of the proposed employment agreement document at any point before the Fair Work Commission formally approved, or the process concluded resulting in the approved agreement."

Each truck at the Super Pit gold mine is capable of carrying up to 240 tonnes. ( ABC News: Jarrod Lucas )

Mr Flynn said he was satisfied Komatsu was unlikely to contravene an enterprise agreement in the future, noting its record and the fact the money was paid.

"The culpability of the company and Mr Morgan is lessened by reason of the genesis of the contravention, that is a typographical error that appeared in the proposed enterprise agreement document and was perpetuated in the approved agreement," he said.

"Of course, it would have been preferable for the company to have in place systems designed to prevent such errors reaching the stage they did in this case."

Union accuses company of 'gouging' workers

AMWU state secretary Steve McCartney was critical of Komatsu's actions, saying it chose to spend money on legal fees fighting the union rather than paying workers what they were owed.

"It's pretty hard to say, 'I accidentally did a 10 instead of a two'," Mr McCartney said.

"I don't think they convinced us or the court.

"It seems to me if that's their argument, they've got to be clutching at straws ... it's almost like 'the dog ate my homework'."

Mr McCartney said "gouging" of workers' pay and entitlements has been "rampant" since the end of the mining investment boom.

"You can't keep breaking the law and think you'll get away with it," he said.

"At the end of the day, when the company makes a bit of extra money, so should these workers.

"These are companies which are on the A-list you might say, as respectable operators in Australia, and when you peel back the onion you start to see they're just like everyone else grabbing profit where they can and gouging workers."

A Komatsu shovel operating in the Super Pit gold mine. ( ABC News: Jarrod Lucas )

Bonus paid in 'good faith'

But Mr Shaw denied that was the case, calling Mr McCartney's comments "typical union propaganda".

He said Komatsu had paid its Super Pit workers bonuses since the first enterprise agreement in 2010, including about $200,000 in bonus payments last year.

That increased to $330,000 in bonuses in April this year, which Mr Shaw said was the equivalent of 8 per cent of a worker's base salary.

Mr Shaw said Komatsu was not obligated to pay this year's bonus as the workers did not meet their KPIs, after the Super Pit operation was badly affected by two major rockfall incidents.

"From our point of view, we've had this agreement going for many years, way back to 2010," he said.

"We've always negotiated with our people and treated them right.

"For example, we paid the bonus this year and we didn't have to pay according to the letter of the law under the enterprise agreement, but we chose to pay it in good faith.

"We've always acted on good terms with our people and we'll continue to do that because they're important to us."