Local media reports suggest water-damaged explosives are still in the ground at the Mt Arthur coal mine, just like the one that led to a plume of poisonous smoke blowing across worksites last month.

Workers have reportedly told Fairfax media outlet The Newcastle Herald that a number of shots remain in the ground, and could now be soaked with water or otherwise damaged. The situation echoes the conditions that led to a botched blasting episode on February 18.

The workers allege that the problem would not exist if the company that owns the mine would use better explosives.

A statement from mine operator BHP Billiton said the company “does not use contaminated blasting material on site” at the Mt Arthur coal dig.

BHP says it will do what it can to prevent another “fume incident”, with plans including “using an explosive that is less susceptible to contamination via water”.

The contamination via water is one of the aspects blamed for an ‘incident’ in mid-February, which saw a plume of poisonous nitrogen dioxide gas spread in smoke across the Muswellbrook industrial estate, leaving several people with respiratory irritation.

“The ongoing use of this explosive will be evaluated based on the outcomes of the investigation,” BHP’s statement said.

“Mt Arthur Coal takes its environmental and community obligations seriously, and continues to work with the EPA and other local government agencies.”

A spokesperson for the company said it would “need to get all the evidence, listen to what the company is telling us, conduct interviews with people from the community, and we will be making no comment until that is completed.”