"Operators found guilty of contravening this ordinance in court could be fined anywhere from RM1,000-RM 10,000," he said.
"They also face the possibility of having their licences suspended or cancelled."
He said those caught overloading for the first time faced the possibility of having to settle a RM300 compound.
The spokesman was responding to a complaint from a Daily Express reader about the overly-long bus ride she had to endure from the town to Kunak when she went home for Hari Raya.
She said it took eight hours, instead of four, for her to reach her destination.
The passenger said the duration of the journey was doubled as the driver made several stops along the way to pick up passengers, all of whom had to stand in the aisle.
She said many of those who were standing were bound for Semporna, the bus's final stop.
She provided the name of the bus company and registration plate number of the vehicle involved, as well as the time and date of the incident.
The spokesman said it would have to verify the resident's claim.
"The firm's management would be queried about what transpired, before further action can be taken," he said.
The reader, Lina, said the bus left the Sandakan terminal at around 7am.
"Just before the bus set off, the driver had to alight to have his papers checked by some officers," she said.
"By this time, all the seats on board were occupied."
After the officers left, more than 10 other passengers were let in, according to her.
"They stood in the aisle which gradually filled up along the trip as we made three more stops before I finally reached my stop at 3pm."
On top of the discomfort caused by the crowded conditions on the bus, she said the vehicle also broke down a few times.
"I overheard one of the passengers saying that the engine was overheating."