According to a report in the ABC, the mines current workers spotted an internet ad on an undisclosed recruitment agency site.

It was believed to be advertising a two-year contract at Norwich, with a request to start immediately.

According to the news service, the advertisement claimed workers would have “the security of a long-term position”

The ABC said a worker currently employed at Norwich saw and applied for the ad, and was told to take his resume in next week.

Union lodge secretary Frank Johnston said the ad indicated that BMA continued to change its story.

“In one breath they're telling the employees they'll place them across other pits,” he was quoted as saying.

“In the next breath they find out that Norwich Park management's selling their jobs.

“It just told me what we suspected, that people weren't being honest and upfront and transparent.”

Construction, Forestry, Mining and Energy Union district president Steve Smyth said BMA was up to dirty tricks.

“At the end of the day, they don't want a permanent workforce at Norwich Park, they want to de-unionise the coal industry – this is a part of it,” Smyth told the ABC.

“It's very apparent now that they want to run the mine with contractors, introduce whatever shift they see fit and have people living in single person's accommodation.”

A BMA spokesman told ILN it was not advertising for staff at Norwich, contrary to workers claims.

The spokesman said the ad was published online on April 3 by a recruitment company of one of its contractors, prior to the announcement to cease operations on April 11.

The advertisement is believed to have been removed.

The ongoing industrial dispute between the BHP Billiton Mitsubishi Alliance and the unions over the latest enterprise agreement forced BMA to declare force majeure across all its operations in early April.

Announcing the closure of Norwich last week, BHP conceded that the mine had been unprofitable for some months, in part due to strike action, high costs and flooding.

BHP’s share of production from Norwich Park was 1 million tonnes as of March 2012, down from 1.9Mt the previous corresponding period.

The announcement is expected to affect 1400 workers employed at the mine.