Federal workforce safety regulators recently cited and fined Exxon Mobil for violations related to an explosion at a Louisiana refinery and chemical plant in November.

The Occupational Safety and Health Administration found nine violations and levied about $165,000 in penalties against the energy giant in May, according to documents reviewed by Reuters this month.

Although OSHA resumed publishing citations on its website after a lengthy hiatus at the beginning of the Trump administration, the Exxon Mobil penalties were not listed. 

The company reportedly told Louisiana regulations that the explosion occurred when a worker removed the cover of a malfunctioning valve and turned a stem using a wrench, which released highly volatile isobutane that was ignited by a welding machine.

The blast injured four workers, including one reportedly knocked off a scaffold and another burned over most of her body.

OSHA cited the company for inadequate employee training as well as failure to properly maintain equipment or carry out required inspections.

Exxon Mobil is contesting the findings and a spokeswoman told Reuters that that "nothing is more important" to the company than the safety of workers and nearby residents.

A separate investigation of the explosion by the U.S. Chemical Safety Board remains ongoing.