The mining union says international company Peabody is attempting to terminate an enterprise agreement (EA) with part of its Helensburgh workforce to try and avoid new federal industrial relations laws.

The Mining and Energy Union (MEU) said this week that Peabody made an application to the Fair Work Commission to terminate an EA covering 18 workers at the Metropolitan Colliery's coal handling and preparation plant.

District secretary Andy Davey said the move was aggressive and disproportionate.

"Peabody at this stage have not bargained in good faith," he said.

"They want to rip out all the job security clauses of the washery and have the boys on a little bit of a shoe-string.

"The company is trying to substantially reduce conditions while only offering a 2 per cent pay rise.

The mine and the union have been involved in a protracted dispute that saw the workers locked out for seven weeks earlier this year.

The Fair Work Commission then told the company to allow the workers to return.

'Trying to beat the legislative clock'

Mr Davey said the union believed Peabody was attempting to scupper the agreement before the federal government's new industrial relations laws came into effect.

"The move comes ahead of the foreshadowed legislation from the Albanese government to restrict employers from terminating enterprise agreements during bargaining," he said.

He said Peabody and the MEU were still participating in a Fair Work Commission process under section 240 of the Fair Work Act to resolve the dispute.

"Peabody should get serious about resolving the dispute with the assistance of the commission rather than trying to beat the legislative clock by trying to tear up the EA," Mr Davey said.

In September Workplace Relations Minister Tony Burke wrote to the Fair Work Commission raising concerns about the capacity of employers to apply "unilaterally" to the commission to terminate EAs as a negotiating strategy.

"The government is concerned by the practice of some employers threatening to terminate agreements as a bargaining tactic," Mr Burke wrote.

The agreement termination changes were part of the package of proposed changes Mr Burke introduced to the parliament this week.

Miner denies accusations

A spokesperson for Peabody has rejected the union's claims.

"Peabody has been negotiating in good faith with 18 employees at our coal wash plant for over a year to lock in increased wages and to remove archaic clauses that prevent us from operating flexibly in a volatile coal market," the spokesperson said.

"We have participated in 18 bargaining sessions, including three facilitated meetings with the Fair Work Commission, and conducted two employee votes without a workable outcome.

"Contrary to union claims, we have no motivation to outsource these roles and in fact transferred these employees from being external contractors to full-time Peabody employees less than three years ago in 2019.