A contractor for Peabody Energy has rushed to apologise for sacking around 100 workers via text message.

Reports say a short note last Thursday night told workers at Peabody’s Burton coking coal mine that their redundancy was looming.

The workers were hired by labour firm Thiess, which now claims its use of a text message was a mistake, but will not say how it managed to pull off such an elaborate and specific accident.

The round of redundancy comes as falling commodity prices push Peabody to cut production levels, slashing output by about 1 million tonnes per year.

It is expected to sack 300 to 350 workers from the Burton site and will target lower-cost reserves with reduced fleets of equipment.

In a written statement to employees, published by industry media, Thiess said it has realised that firing workers in the least personal way possible was an “error in judgement”.

“Crews were advised during recent presentations we would bulk SMS and phone call to communicate progress, however it was an error in judgement to use the SMS option as a means of notifying impacted mining operators of redundancy,” Thiess said.

“Impacted workshop and CHP personnel were notified in person, we apologise for any distress caused.”

“Our Burton team was advised of our client’s intention to scale down operations through a series of presentations held in early August,” Thiess said in a separate statement, released to the press on Friday.

“Crews were advised that bulk SMS and phone calls may be used to communicate progress, however the use of SMS in this instance was an error and we apologise.

“Other affected personnel were notified in person.”

The Construction Forestry Mining and Energy Union (CFMEU) is outraged.

“For a company that always talks about itself being a family orientated company; that Thiess is a family, it's not just a name; to be told after a number of years of service just by popping it on an email address, that's pretty poor,” CFMEU district vice president Steve Pierce said.

“We haven't seen this sort of nonsense since the darkest days of the Howard era.”