The EPA claims both incidents allegedly took place at Whitehaven's Maules Creek mine near Boggabri.

"The EPA is investigating allegations of blast fume emissions following blasts at Maules Creek Coal Mine on 7 October and 9 November 2021," a spokesperson said.

Environmental group Lock the Gate Alliance said the consequences could be significant if the blasts did go wrong.

Lock the Gate spokeswoman Georgina Woods said the negative outcomes could effect both the nearby wildlife and people who live in the area.

"Blasting, if carried out in an unsafe manner, can release toxic fumes and can negatively impact human health and the health of the local environment," she said.

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She also said that should Whitehaven be found guilty of any wrongdoing, it was time for the EPA to "throw the book at the company".

"Whitehaven is yet to face sufficient disciplinary action to reduce the frequency and severity of crimes it commits at its Northern NSW coal mines, despite more than 35 fines, prosecutions, or warnings," she said.

"The maximum penalty the EPA can impose without prosecution is just $15,000 per offence and that is less than half an hour of current coal production at one mine for this company.

"We're at the point where escalation is necessary because the fines and warnings issued so far are clearly not working to make Whitehaven clean up its act."

The group has in the past called for harsher penalties, after not being satisfied with fines handed out for incidents that occurred at its Narrabri Coal and Tarrawonga Coal mines earlier this year.

The Leader contacted Whitehaven for comment on the investigation at its Maules Creek mine, but it declined.